Merge remote-tracking branch 'nlohmann/develop' into iterate-on-destruction

.circleci/config.yml

+version: 2
+jobs:
+  build:
+    docker:
+      - image: debian:stretch
+
+    steps:
+      - checkout
+
+      - run:
+          name: Install sudo
+          command: 'apt-get update && apt-get install -y sudo && rm -rf /var/lib/apt/lists/*'
+      - run:
+          name: Install GCC
+          command: 'apt-get update && apt-get install -y gcc g++'
+      - run:
+          name: Install CMake
+          command: 'apt-get update && sudo apt-get install -y cmake'
+      - run:
+          name: Create build files
+          command: 'mkdir build ; cd build ; cmake ..'
+      - run:
+          name: Versions
+          command: 'g++ --version ; uname -a'
+      - run:
+          name: Compile
+          command: 'cmake --build build'
+      - run:
+          name: Execute test suite
+          command: 'cd build ; ctest -j 2'

.clang-tidy

+Checks: '-*,
+         bugprone-*,
+         cert-*,
+         clang-analyzer-*,
+         google-*,
+         -google-runtime-references,
+         -google-explicit-constructor,
+         hicpp-*,
+         -hicpp-no-array-decay,
+         -hicpp-uppercase-literal-suffix,
+         -hicpp-explicit-conversions,
+         misc-*,
+         -misc-non-private-member-variables-in-classes,
+         llvm-*,
+         -llvm-header-guard,
+         modernize-*,
+         -modernize-use-trailing-return-type,
+         performance-*,
+         portability-*,
+         readability-*,
+         -readability-magic-numbers,
+         -readability-uppercase-literal-suffix'
+
+CheckOptions:
+  - key: hicpp-special-member-functions.AllowSoleDefaultDtor
+    value: 1

.doozer.json

+{
+  "targets": {
+    "raspbian-jessie": {
+      "buildenv": "raspbian-jessie",
+      "builddeps": ["build-essential", "wget"],
+      "buildcmd": [
+      	"uname -a",
+        "cat /etc/os-release",
+        "g++ --version",
+      	"cd",
+      	"wget https://github.com/Kitware/CMake/releases/download/v3.14.0/cmake-3.14.0.tar.gz",
+      	"tar xfz cmake-3.14.0.tar.gz",
+      	"cd cmake-3.14.0",
+      	"./bootstrap",
+      	"make -j8",
+      	"cd",
+      	"mkdir build",
+      	"cd build",
+      	"../cmake-3.14.0/bin/cmake /project/repo/checkout",
+      	"make -j8",
+      	"../cmake-3.14.0/bin/ctest -VV -j4 --timeout 10000"
+      ]
+    },
+    "xenial-armhf": {
+      "buildenv": "xenial-armhf",
+      "builddeps": ["build-essential", "wget"],
+      "buildcmd": [
+        "uname -a",
+        "lsb_release -a",
+        "g++ --version",
+        "cd",
+        "wget --no-check-certificate https://github.com/Kitware/CMake/releases/download/v3.14.0/cmake-3.14.0.tar.gz",
+        "tar xfz cmake-3.14.0.tar.gz",
+        "cd cmake-3.14.0",
+        "./bootstrap",
+        "make -j8",
+        "cd",
+        "mkdir build",
+        "cd build",
+        "../cmake-3.14.0/bin/cmake /project/repo/checkout",
+        "make -j8",
+        "../cmake-3.14.0/bin/ctest -VV -j4 --timeout 10000"
+      ]
+    },
+    "fedora24-x86_64": {
+      "buildenv": "fedora24-x86_64",
+      "builddeps": ["cmake", "make", "gcc gcc-c++"],
+      "buildcmd": [
+      	"uname -a",
+        "cat /etc/fedora-release",
+        "g++ --version",
+      	"cd",
+      	"mkdir build",
+      	"cd build",
+      	"cmake /project/repo/checkout",
+      	"make -j8",
+      	"ctest -VV -j8"
+      ]
+    },
+    "centos7-x86_64": {
+      "buildenv": "centos7-x86_64",
+      "builddeps": ["make", "wget", "gcc-c++"],
+      "buildcmd": [
+      	"uname -a",
+        "rpm -q centos-release",
+        "g++ --version",
+      	"cd",
+      	"wget https://github.com/Kitware/CMake/releases/download/v3.14.0/cmake-3.14.0.tar.gz",
+      	"tar xfz cmake-3.14.0.tar.gz",
+      	"cd cmake-3.14.0",
+      	"./bootstrap",
+      	"make -j8",
+      	"cd",
+      	"mkdir build",
+      	"cd build",
+      	"../cmake-3.14.0/bin/cmake /project/repo/checkout",
+      	"make -j8",
+      	"../cmake-3.14.0/bin/ctest -VV -j8"
+      ]
+    }
+  }
+}

.github/CODEOWNERS

+# JSON for Modern C++ has been originally written by Niels Lohmann.
+# Since 2013 over 140 contributors have helped to improve the library.
+# This CODEOWNERS file is only to make sure that @nlohmann is requsted
+# for a code review in case of a pull request.
+
+* @nlohmann

.github/CONTRIBUTING.md

@@ -4,7 +4,7 @@
 
 This project started as a little excuse to exercise some of the cool new C++11 features. Over time, people actually started to use the JSON library (yey!) and started to help improve it by proposing features, finding bugs, or even fixing my mistakes. I am really [thankful](https://github.com/nlohmann/json/blob/master/README.md#thanks) for this and try to keep track of all the helpers.
 
-To make it as easy as possible for you to contribute and for me to keep an overview, here are a few guidelines which should help us avoid all kinds of unnecessary work or disappointment. And of course, this document is subject to discussion, so please [create an issue](https://github.com/nlohmann/json/issues/new) or a pull request if you find a way to improve it!
+To make it as easy as possible for you to contribute and for me to keep an overview, here are a few guidelines which should help us avoid all kinds of unnecessary work or disappointment. And of course, this document is subject to discussion, so please [create an issue](https://github.com/nlohmann/json/issues/new/choose) or a pull request if you find a way to improve it!
 
 ## Private reports
 
@@ -12,7 +12,7 @@ Usually, all issues are tracked publicly on [GitHub](https://github.com/nlohmann
 
 ## Prerequisites
 
-Please [create an issue](https://github.com/nlohmann/json/issues/new), assuming one does not already exist, and describe your concern. Note you need a [GitHub account](https://github.com/signup/free) for this.
+Please [create an issue](https://github.com/nlohmann/json/issues/new/choose), assuming one does not already exist, and describe your concern. Note you need a [GitHub account](https://github.com/signup/free) for this.
 
 ## Describe your issue
 
@@ -22,7 +22,7 @@ Clearly describe the issue:
 - If you propose a change or addition, try to give an **example** how 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.
 
-Please stick to the [issue template](https://github.com/nlohmann/json/blob/develop/.github/ISSUE_TEMPLATE.md) if possible.
+Please stick to the provided issue templates ([bug report](https://github.com/nlohmann/json/blob/develop/.github/ISSUE_TEMPLATE/Bug_report.md), [feature request](https://github.com/nlohmann/json/blob/develop/.github/ISSUE_TEMPLATE/Feature_request.md), or [question](https://github.com/nlohmann/json/blob/develop/.github/ISSUE_TEMPLATE/question.md)) if possible.
 
 ## Files to change
 
@@ -32,7 +32,7 @@ To make changes, you need to edit the following files:
 
 1. [`include/nlohmann/*`](https://github.com/nlohmann/json/tree/develop/include/nlohmann) - These files are the sources of the library. Before testing or creating a pull request, execute `make amalgamate` to regenerate `single_include/nlohmann/json.hpp`.
 
-2. [`test/src/unit-*.cpp`](https://github.com/nlohmann/json/tree/develop/test/src) - These files contain the [Catch](https://github.com/philsquared/Catch) unit tests which currently cover [100 %](https://coveralls.io/github/nlohmann/json) of the library's code.
+2. [`test/src/unit-*.cpp`](https://github.com/nlohmann/json/tree/develop/test/src) - These files contain the [doctest](https://github.com/onqtam/doctest) unit tests which currently cover [100 %](https://coveralls.io/github/nlohmann/json) of the library's code.
 
    If you add or change a feature, please also add a unit test to this file. The unit tests can be compiled and executed with
 

.github/FUNDING.yml

+custom: http://paypal.me/nlohmann

.github/ISSUE_TEMPLATE/Bug_report.md

----
-name: Bug report
-about: Create a report to help us improve
-
----
-
-- What is the issue you have?
-
-- Please describe the steps to reproduce the issue. Can you provide a small but working code example?
-
-- What is the expected behavior?
-
-- And what is the actual behavior instead?
-
-- Which compiler and operating system are you using? Is it a [supported compiler](https://github.com/nlohmann/json#supported-compilers)?
-
-- Did you use a released version of the library or the version from the `develop` branch?
-
-- If you experience a compilation error: can you [compile and run the unit tests](https://github.com/nlohmann/json#execute-unit-tests)?
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: 'kind: bug'
+assignees: ''
+
+---
+
+- What is the issue you have?
+
+- Please describe the steps to reproduce the issue. Can you provide a small but working code example?
+
+- What is the expected behavior?
+
+- And what is the actual behavior instead?
+
+- Which compiler and operating system are you using? Is it a [supported compiler](https://github.com/nlohmann/json#supported-compilers)?
+
+- Did you use a released version of the library or the version from the `develop` branch?
+
+- If you experience a compilation error: can you [compile and run the unit tests](https://github.com/nlohmann/json#execute-unit-tests)?

.github/ISSUE_TEMPLATE/Feature_request.md

----
-name: Feature request
-about: Suggest an idea for this project
-
----
-
-- Describe the feature in as much detail as possible.
-
-- Include sample usage where appropriate.
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: 'kind: enhancement/improvement'
+assignees: ''
+
+---
+
+- Describe the feature in as much detail as possible.
+
+- Include sample usage where appropriate.

.github/ISSUE_TEMPLATE/question.md

+---
+name: Question
+about: Ask a question regarding the library.
+title: ''
+labels: 'kind: question'
+assignees: ''
+
+---
+
+- Describe what you want to achieve.
+
+- Describe what you tried.
+
+- Describe which system (OS, compiler) you are using.
+
+- Describe which version of the library you are using (release version, develop branch).

.github/SECURITY.md

+# Security Policy
+
+## Reporting a Vulnerability
+
+Usually, all issues are tracked publicly on [GitHub](https://github.com/nlohmann/json/issues). If you want to make a private report (e.g., for a vulnerability or to attach an example that is not meant to be published), please send an email to <mail@nlohmann.me>. You can use [this key](https://keybase.io/nlohmann/pgp_keys.asc?fingerprint=797167ae41c0a6d9232e48457f3cea63ae251b69) for encryption.

.github/workflows/ccpp.yml

+name: C/C++ CI
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    
+    steps:
+    - uses: actions/checkout@v1
+    - name: prepare
+      run: mkdir build
+    - name: cmake
+      run: cd build ; cmake ..
+    - name: build
+      run: make -C build
+    - name: test
+      run: cd build ; ctest -j 10

.travis.yml

@@ -43,12 +43,15 @@ matrix:
   - os: linux
     compiler: clang
     env:
-      - COMPILER=clang++-5.0
+      - COMPILER=clang++-7
       - CMAKE_OPTIONS=-DJSON_Sanitizer=ON
+      - UBSAN_OPTIONS=print_stacktrace=1,suppressions=$(pwd)/test/src/UBSAN.supp
     addons:
       apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-5.0']
-        packages: ['g++-6', 'clang-5.0', 'ninja-build']
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-7']
+        packages: ['g++-6', 'clang-7', 'ninja-build']
+    before_script:
+      - export PATH=$PATH:/usr/lib/llvm-7/bin
 
   # cppcheck
   - os: linux
@@ -128,21 +131,6 @@ matrix:
 
   # OSX / Clang
 
-  - os: osx
-    osx_image: xcode6.4
-
-  - os: osx
-    osx_image: xcode7.3
-
-  - os: osx
-    osx_image: xcode8
-
-  - os: osx
-    osx_image: xcode8.1
-
-  - os: osx
-    osx_image: xcode8.2
-
   - os: osx
     osx_image: xcode8.3
 
@@ -164,11 +152,17 @@ matrix:
   - os: osx
     osx_image: xcode10
 
+  - os: osx
+    osx_image: xcode10.1
+
+  - os: osx
+    osx_image: xcode10.2
+
   # Linux / GCC
 
   - os: linux
     compiler: gcc
-    env: compiler=g++-4.8
+    env: COMPILER=g++-4.8
     addons:
       apt:
         sources: ['ubuntu-toolchain-r-test']
@@ -176,7 +170,7 @@ matrix:
 
   - os: linux
     compiler: gcc
-    env: compiler=g++-4.9
+    env: COMPILER=g++-4.9
     addons:
       apt:
         sources: ['ubuntu-toolchain-r-test']
@@ -214,15 +208,23 @@ matrix:
         sources: ['ubuntu-toolchain-r-test']
         packages: ['g++-8', 'ninja-build']
 
+  - os: linux
+    compiler: gcc
+    env: COMPILER=g++-9
+    addons:
+      apt:
+        sources: ['ubuntu-toolchain-r-test']
+        packages: ['g++-9', 'ninja-build']
+
   - os: linux
     compiler: gcc
     env:
-      - COMPILER=g++-8
-      - CXXFLAGS=-std=c++17
+      - COMPILER=g++-9
+      - CXXFLAGS=-std=c++2a
     addons:
       apt:
         sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-8', 'ninja-build']
+        packages: ['g++-9', 'ninja-build']
 
   # Linux / Clang
 
@@ -290,15 +292,23 @@ matrix:
         sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-6.0']
         packages: ['g++-6', 'clang-6.0', 'ninja-build']
 
+  - os: linux
+    compiler: clang
+    env: COMPILER=clang++-7
+    addons:
+      apt:
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-7']
+        packages: ['g++-6', 'clang-7', 'ninja-build']
+
   - os: linux
     compiler: clang
     env:
-      - COMPILER=clang++-6.0
+      - COMPILER=clang++-7
       - CXXFLAGS=-std=c++1z
     addons:
       apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-6.0']
-        packages: ['g++-6', 'clang-6.0', 'ninja-build']
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-7']
+        packages: ['g++-6', 'clang-7', 'ninja-build']
 
 ################
 # build script #
@@ -326,7 +336,7 @@ script:
   # compile and execute unit tests
   - mkdir -p build && cd build
   - cmake .. ${CMAKE_OPTIONS} -DJSON_MultipleHeaders=${MULTIPLE_HEADERS} -GNinja && cmake --build . --config Release
-  - ctest -C Release -V -j
+  - ctest -C Release --timeout 2700 -V -j
   - cd ..
 
   # check if homebrew works (only checks develop branch)   

.whitesource

+{
+  "checkRunSettings": {
+    "vulnerableCheckRunConclusionLevel": "failure"
+  },
+  "issueSettings": {
+    "minSeverityLevel": "LOW"
+  }
+}
\ No newline at end of file

CMakeLists.txt

@@ -4,7 +4,7 @@ cmake_minimum_required(VERSION 3.1)
 ## PROJECT
 ## name and version
 ##
-project(nlohmann_json VERSION 3.5.0 LANGUAGES CXX)
+project(nlohmann_json VERSION 3.7.1 LANGUAGES CXX)
 
 ##
 ## INCLUDE
@@ -16,15 +16,17 @@ include(ExternalProject)
 ## OPTIONS
 ##
 option(JSON_BuildTests "Build the unit tests when BUILD_TESTING is enabled." ON)
+option(JSON_Install "Install CMake targets during install step." ON)
 option(JSON_MultipleHeaders "Use non-amalgamated version of the library." OFF)
 
 ##
 ## CONFIGURATION
 ##
+include(GNUInstallDirs)
+
 set(NLOHMANN_JSON_TARGET_NAME               ${PROJECT_NAME})
-set(NLOHMANN_JSON_CONFIG_INSTALL_DIR        "lib/cmake/${PROJECT_NAME}"
-  CACHE INTERNAL "")
-set(NLOHMANN_JSON_INCLUDE_INSTALL_DIR       "include")
+set(NLOHMANN_JSON_CONFIG_INSTALL_DIR        "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}" CACHE INTERNAL "")
+set(NLOHMANN_JSON_INCLUDE_INSTALL_DIR       "${CMAKE_INSTALL_INCLUDEDIR}")
 set(NLOHMANN_JSON_TARGETS_EXPORT_NAME       "${PROJECT_NAME}Targets")
 set(NLOHMANN_JSON_CMAKE_CONFIG_TEMPLATE     "cmake/config.cmake.in")
 set(NLOHMANN_JSON_CMAKE_CONFIG_DIR          "${CMAKE_CURRENT_BINARY_DIR}")
@@ -46,7 +48,11 @@ endif()
 ##
 add_library(${NLOHMANN_JSON_TARGET_NAME} INTERFACE)
 add_library(${PROJECT_NAME}::${NLOHMANN_JSON_TARGET_NAME} ALIAS ${NLOHMANN_JSON_TARGET_NAME})
-target_compile_features(${NLOHMANN_JSON_TARGET_NAME} INTERFACE cxx_std_11)
+if (${CMAKE_VERSION} VERSION_LESS "3.8.0")
+    target_compile_features(${NLOHMANN_JSON_TARGET_NAME} INTERFACE cxx_range_for)
+else()
+    target_compile_features(${NLOHMANN_JSON_TARGET_NAME} INTERFACE cxx_std_11)
+endif()
 
 target_include_directories(
     ${NLOHMANN_JSON_TARGET_NAME}
@@ -92,32 +98,34 @@ configure_file(
     @ONLY
 )
 
-install(
-    DIRECTORY ${NLOHMANN_JSON_INCLUDE_BUILD_DIR}
-    DESTINATION ${NLOHMANN_JSON_INCLUDE_INSTALL_DIR}
-)
-install(
-    FILES ${NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE} ${NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE}
-    DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
-)
-if (NLOHMANN_ADD_NATVIS)
+if(JSON_Install)
     install(
-        FILES ${NLOHMANN_NATVIS_FILE}
-        DESTINATION .
-)
+        DIRECTORY ${NLOHMANN_JSON_INCLUDE_BUILD_DIR}
+        DESTINATION ${NLOHMANN_JSON_INCLUDE_INSTALL_DIR}
+    )
+    install(
+        FILES ${NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE} ${NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE}
+        DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
+    )
+    if (NLOHMANN_ADD_NATVIS)
+        install(
+            FILES ${NLOHMANN_NATVIS_FILE}
+            DESTINATION .
+    )
+    endif()
+    export(
+        TARGETS ${NLOHMANN_JSON_TARGET_NAME}
+        NAMESPACE ${PROJECT_NAME}::
+        FILE ${NLOHMANN_JSON_CMAKE_PROJECT_TARGETS_FILE}
+    )
+    install(
+        TARGETS ${NLOHMANN_JSON_TARGET_NAME}
+        EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
+        INCLUDES DESTINATION ${NLOHMANN_JSON_INCLUDE_INSTALL_DIR}
+    )
+    install(
+        EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
+        NAMESPACE ${PROJECT_NAME}::
+        DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
+    )
 endif()
-export(
-    TARGETS ${NLOHMANN_JSON_TARGET_NAME}
-    NAMESPACE ${PROJECT_NAME}::
-    FILE ${NLOHMANN_JSON_CMAKE_PROJECT_TARGETS_FILE}
-)
-install(
-    TARGETS ${NLOHMANN_JSON_TARGET_NAME}
-    EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
-    INCLUDES DESTINATION ${NLOHMANN_JSON_INCLUDE_INSTALL_DIR}
-)
-install(
-    EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
-    NAMESPACE ${PROJECT_NAME}::
-    DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
-)

LICENSE.MIT

 MIT License 
 
-Copyright (c) 2013-2018 Niels Lohmann
+Copyright (c) 2013-2019 Niels Lohmann
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

appveyor.yml

@@ -3,6 +3,43 @@ version: '{build}'
 environment:
   matrix:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      configuration: Debug
+      platform: x86
+      CXX_FLAGS: ""
+      LINKER_FLAGS: ""
+      GENERATOR: Visual Studio 14 2015
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      configuration: Debug
+      platform: x86
+      CXX_FLAGS: ""
+      LINKER_FLAGS: ""
+      GENERATOR: Visual Studio 15 2017
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      configuration: Debug
+      platform: x86
+      CXX_FLAGS: ""
+      LINKER_FLAGS: ""
+      GENERATOR: Visual Studio 16 2019
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      configuration: Debug
+      platform: x64
+      CXX_FLAGS: ""
+      LINKER_FLAGS: ""
+      GENERATOR: Visual Studio 16 2019
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      configuration: Debug
+      COMPILER: mingw
+      platform: x86
+      CXX_FLAGS: ""
+      LINKER_FLAGS: ""
+      GENERATOR: Ninja
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      configuration: Release
       COMPILER: mingw
       platform: x86
       CXX_FLAGS: ""
@@ -10,57 +47,80 @@ environment:
       GENERATOR: Ninja
 
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      configuration: Release
       platform: x86
       CXX_FLAGS: ""
       LINKER_FLAGS: ""
       GENERATOR: Visual Studio 14 2015
 
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      configuration: Release
       platform: x86
+      name: with_win_header
       CXX_FLAGS: ""
       LINKER_FLAGS: ""
-      GENERATOR: Visual Studio 15 2017
+      GENERATOR: Visual Studio 14 2015
 
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      configuration: Release
       platform: x86
       CXX_FLAGS: "/permissive- /std:c++latest /utf-8"
       LINKER_FLAGS: ""
       GENERATOR: Visual Studio 15 2017
 
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-      platform: x64
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      configuration: Release
+      platform: x86
       CXX_FLAGS: ""
       LINKER_FLAGS: ""
-      GENERATOR: Visual Studio 14 2015 Win64
+      GENERATOR: Visual Studio 16 2019
 
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      configuration: Release
       platform: x64
       CXX_FLAGS: ""
       LINKER_FLAGS: ""
-      GENERATOR: Visual Studio 15 2017 Win64
+      GENERATOR: Visual Studio 14 2015
 
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      configuration: Release
       platform: x64
       CXX_FLAGS: "/permissive- /std:c++latest /utf-8 /F4000000"
       LINKER_FLAGS: "/STACK:4000000"
-      GENERATOR: Visual Studio 15 2017 Win64
+      GENERATOR: Visual Studio 15 2017
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      configuration: Release
+      platform: x64
+      CXX_FLAGS: ""
+      LINKER_FLAGS: ""
+      GENERATOR: Visual Studio 16 2019
 
 init:
   - cmake --version
   - msbuild /version
 
 install:
-  - if "%COMPILER%"=="mingw" appveyor DownloadFile https://github.com/ninja-build/ninja/releases/download/v1.6.0/ninja-win.zip -FileName ninja.zip
-  - if "%COMPILER%"=="mingw" 7z x ninja.zip -oC:\projects\deps\ninja > nul
-  - if "%COMPILER%"=="mingw" set PATH=C:\projects\deps\ninja;%PATH%
-  - if "%COMPILER%"=="mingw" set PATH=C:\mingw-w64\x86_64-7.3.0-posix-seh-rt_v5-rev0\mingw64\bin;%PATH%
-  - if "%COMPILER%"=="mingw" g++ --version
+  - if "%COMPILER%"=="mingw"  appveyor DownloadFile https://github.com/ninja-build/ninja/releases/download/v1.6.0/ninja-win.zip -FileName ninja.zip
+  - if "%COMPILER%"=="mingw"  7z x ninja.zip -oC:\projects\deps\ninja > nul
+  - if "%COMPILER%"=="mingw"  set PATH=C:\projects\deps\ninja;%PATH%
+  - if "%COMPILER%"=="mingw"  set PATH=C:\mingw-w64\x86_64-7.3.0-posix-seh-rt_v5-rev0\mingw64\bin;%PATH%
+  - if "%COMPILER%"=="mingw"  g++ --version
+  - if "%platform%"=="x86"    set GENERATOR_PLATFORM=Win32
 
 before_build:
-  - cmake . -G "%GENERATOR%" -DCMAKE_CXX_FLAGS="%CXX_FLAGS%" -DCMAKE_EXE_LINKER_FLAGS="%LINKER_FLAGS%" -DCMAKE_IGNORE_PATH="C:/Program Files/Git/usr/bin"
+  # for with_win_header build, inject the inclusion of Windows.h to the single-header library
+  - ps: if ($env:name -Eq "with_win_header") { $header_path = "single_include\nlohmann\json.hpp" }
+  - ps: if ($env:name -Eq "with_win_header") { "#include <Windows.h>`n" + (Get-Content $header_path | Out-String) | Set-Content $header_path }
+  - if "%GENERATOR%"=="Ninja" (cmake . -G "%GENERATOR%" -DCMAKE_BUILD_TYPE="%configuration%" -DCMAKE_CXX_FLAGS="%CXX_FLAGS%" -DCMAKE_EXE_LINKER_FLAGS="%LINKER_FLAGS%" -DCMAKE_IGNORE_PATH="C:/Program Files/Git/usr/bin") else (cmake . -G "%GENERATOR%" -A "%GENERATOR_PLATFORM%" -DCMAKE_CXX_FLAGS="%CXX_FLAGS%" -DCMAKE_EXE_LINKER_FLAGS="%LINKER_FLAGS%" -DCMAKE_IGNORE_PATH="C:/Program Files/Git/usr/bin")
 
 build_script:
-  - cmake --build . --config Release
+  - cmake --build . --config "%configuration%"
 
 test_script:
-  - ctest -C Release -V -j
+  - if "%configuration%"=="Release" ctest -C "%configuration%" -V -j
+  # On Debug builds, skip test-unicode_all
+  # as it is extremely slow to run and cause
+  # occasional timeouts on AppVeyor.
+  # More info: https://github.com/nlohmann/json/pull/1570
+  - if "%configuration%"=="Debug" ctest --exclude-regex "test-unicode_all" -C "%configuration%" -V -j

benchmarks/CMakeLists.txt

-cmake_minimum_required(VERSION 3.1)
+cmake_minimum_required(VERSION 3.8)
 project(JSON_Benchmarks LANGUAGES CXX)
 
 # set compiler flags

doc/Doxyfile

-# Doxyfile 1.8.15
+# Doxyfile 1.8.16
 
 #---------------------------------------------------------------------------
 # Project related configuration options
 #---------------------------------------------------------------------------
 DOXYFILE_ENCODING      = UTF-8
 PROJECT_NAME           = "JSON for Modern C++"
-PROJECT_NUMBER         = 3.5.0
+PROJECT_NUMBER         = 3.7.1
 PROJECT_BRIEF          =
 PROJECT_LOGO           =
 OUTPUT_DIRECTORY       = .
@@ -38,6 +38,7 @@ OPTIMIZE_OUTPUT_FOR_C  = NO
 OPTIMIZE_OUTPUT_JAVA   = NO
 OPTIMIZE_FOR_FORTRAN   = NO
 OPTIMIZE_OUTPUT_VHDL   = NO
+OPTIMIZE_OUTPUT_SLICE  = NO
 EXTENSION_MAPPING      =
 MARKDOWN_SUPPORT       = YES
 TOC_INCLUDE_HEADINGS   = 0
@@ -141,7 +142,7 @@ USE_HTAGS              = NO
 VERBATIM_HEADERS       = NO
 CLANG_ASSISTED_PARSING = YES
 CLANG_OPTIONS          = -std=c++11
-CLANG_COMPILATION_DATABASE_PATH                                        = 0
+CLANG_DATABASE_PATH    =
 #---------------------------------------------------------------------------
 # Configuration options related to the alphabetical class index
 #---------------------------------------------------------------------------
@@ -214,6 +215,7 @@ GENERATE_LATEX         = NO
 LATEX_OUTPUT           = latex
 LATEX_CMD_NAME         = latex
 MAKEINDEX_CMD_NAME     = makeindex
+LATEX_MAKEINDEX_CMD    = \makeindex
 COMPACT_LATEX          = NO
 PAPER_TYPE             = a4
 EXTRA_PACKAGES         =
@@ -228,6 +230,7 @@ LATEX_HIDE_INDICES     = NO
 LATEX_SOURCE_CODE      = NO
 LATEX_BIB_STYLE        = plain
 LATEX_TIMESTAMP        = NO
+LATEX_EMOJI_DIRECTORY  =
 #---------------------------------------------------------------------------
 # Configuration options related to the RTF output
 #---------------------------------------------------------------------------
@@ -252,6 +255,7 @@ MAN_LINKS              = NO
 GENERATE_XML           = YES
 XML_OUTPUT             = xml
 XML_PROGRAMLISTING     = YES
+XML_NS_MEMB_FILE_SCOPE = NO
 #---------------------------------------------------------------------------
 # Configuration options related to the DOCBOOK output
 #---------------------------------------------------------------------------

doc/Makefile

@@ -61,6 +61,8 @@ doxygen: create_output create_links
 	$(SED) -i 's@template<template< typename U, typename V, typename... Args > class ObjectType = std::map, template< typename U, typename... Args > class ArrayType = std::vector, class StringType = std::string, class BooleanType = bool, class NumberIntegerType = std::int64_t, class NumberUnsignedType = std::uint64_t, class NumberFloatType = double, template< typename U > class AllocatorType = std::allocator, template< typename T, typename SFINAE=void > class JSONSerializer = adl_serializer>@@g' html/*.html
 	$(SED) -i 's@< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer >@@g' html/*.html
 	$(SED) -i 's@< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType, JSONSerializer >@@g' html/*.html
+	$(SED) -i 's@JSON_HEDLEY_RETURNS_NON_NULL@@g' html/*.html
+	$(SED) -i 's@JSON_HEDLEY_WARN_UNUSED_RESULT@@g' html/*.html
 
 upload: clean doxygen check_output
 	scripts/git-update-ghpages nlohmann/json html

doc/examples/README.link

-<a target="_blank" href="https://wandbox.org/permlink/jhAlfAa9ZPKTp8JK"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/aMsX89i37S5EFFt2"><b>online</b></a>
\ No newline at end of file

doc/examples/contains.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create some JSON values
+    json j_object = R"( {"key": "value"} )"_json;
+    json j_array = R"( [1, 2, 3] )"_json;
+
+    // call contains
+    std::cout << std::boolalpha <<
+              "j_object contains 'key': " << j_object.contains("key") << '\n' <<
+              "j_object contains 'another': " << j_object.contains("another") << '\n' <<
+              "j_array contains 'key': " << j_array.contains("key") << std::endl;
+}

doc/examples/contains.link

+<a target="_blank" href="https://wandbox.org/permlink/iHSlXjtjhgO9Q1Tw"><b>online</b></a>
\ No newline at end of file

doc/examples/contains.output

+j_object contains 'key': true
+j_object contains 'another': false
+j_array contains 'key': false

doc/examples/contains_json_pointer.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create a JSON value
+    json j =
+    {
+        {"number", 1}, {"string", "foo"}, {"array", {1, 2}}
+    };
+
+    std::cout << std::boolalpha
+              << j.contains("/number"_json_pointer) << '\n'
+              << j.contains("/string"_json_pointer) << '\n'
+              << j.contains("/string"_json_pointer) << '\n'
+              << j.contains("/array"_json_pointer) << '\n'
+              << j.contains("/array/1"_json_pointer) << '\n'
+              << j.contains("/array/-"_json_pointer) << '\n'
+              << j.contains("/array/4"_json_pointer) << '\n'
+              << j.contains("/baz"_json_pointer) << std::endl;
+
+    // out_of_range.106
+    try
+    {
+        // try to use an array index with leading '0'
+        j.contains("/array/01"_json_pointer);
+    }
+    catch (json::parse_error& e)
+    {
+        std::cout << e.what() << '\n';
+    }
+
+    // out_of_range.109
+    try
+    {
+        // try to use an array index that is not a number
+        j.contains("/array/one"_json_pointer);
+    }
+    catch (json::parse_error& e)
+    {
+        std::cout << e.what() << '\n';
+    }
+}

doc/examples/contains_json_pointer.link

+<a target="_blank" href="https://wandbox.org/permlink/3TJ79OzHP4vmN1Nb"><b>online</b></a>
\ No newline at end of file

doc/examples/contains_json_pointer.output

+true
+true
+true
+true
+true
+false
+false
+false
+[json.exception.parse_error.106] parse error: array index '01' must not begin with '0'
+[json.exception.parse_error.109] parse error: array index 'one' is not a number

doc/examples/json_pointer__back.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // different JSON Pointers
+    json::json_pointer ptr1("/foo");
+    json::json_pointer ptr2("/foo/0");
+
+    // call empty()
+    std::cout << "last reference token of " << ptr1 << " is " << ptr1.back() << '\n'
+              << "last reference token of " << ptr2 << " is " << ptr2.back() << std::endl;
+}

doc/examples/json_pointer__back.link

+<a target="_blank" href="https://wandbox.org/permlink/2q7gu0ZAQoMeOaAc"><b>online</b></a>
\ No newline at end of file

doc/examples/json_pointer__back.output

+last reference token of "/foo" is foo
+last reference token of "/foo/0" is 0

doc/examples/json_pointer__empty.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // different JSON Pointers
+    json::json_pointer ptr0;
+    json::json_pointer ptr1("");
+    json::json_pointer ptr2("/foo");
+    json::json_pointer ptr3("/foo/0");
+
+    // call empty()
+    std::cout << std::boolalpha
+              << ptr0 << ": " << ptr0.empty() << '\n'
+              << ptr1 << ": " << ptr1.empty() << '\n'
+              << ptr2 << ": " << ptr2.empty() << '\n'
+              << ptr3 << ": " << ptr3.empty() << std::endl;
+}

doc/examples/json_pointer__empty.link

+<a target="_blank" href="https://wandbox.org/permlink/pqG2Q8bmj9SvSX0i"><b>online</b></a>
\ No newline at end of file

doc/examples/json_pointer__empty.output

+"": true
+"": true
+"/foo": false
+"/foo/0": false

doc/examples/json_pointer__operator_add.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create a JSON pointer
+    json::json_pointer ptr("/foo");
+    std::cout << ptr << '\n';
+
+    // append a JSON Pointer
+    ptr /= json::json_pointer("/bar/baz");
+    std::cout << ptr << '\n';
+
+    // append a string
+    ptr /= "fob";
+    std::cout << ptr << '\n';
+
+    // append an array index
+    ptr /= 42;
+    std::cout << ptr << std::endl;
+}

doc/examples/json_pointer__operator_add.link

+<a target="_blank" href="https://wandbox.org/permlink/B8QFt317rARJWiGI"><b>online</b></a>
\ No newline at end of file

doc/examples/json_pointer__operator_add.output

+"/foo"
+"/foo/bar/baz"
+"/foo/bar/baz/fob"
+"/foo/bar/baz/fob/42"

doc/examples/json_pointer__operator_add_binary.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create a JSON pointer
+    json::json_pointer ptr("/foo");
+
+    // append a JSON Pointer
+    std::cout << ptr / json::json_pointer("/bar/baz") << '\n';
+
+    // append a string
+    std::cout << ptr / "fob" << '\n';
+
+    // append an array index
+    std::cout << ptr / 42 << std::endl;
+}

doc/examples/json_pointer__operator_add_binary.link

+<a target="_blank" href="https://wandbox.org/permlink/SEuKMiM0vuzQDU8U"><b>online</b></a>
\ No newline at end of file

doc/examples/json_pointer__operator_add_binary.output

+"/foo/bar/baz"
+"/foo/fob"
+"/foo/42"

doc/examples/json_pointer__parent_pointer.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // different JSON Pointers
+    json::json_pointer ptr1("");
+    json::json_pointer ptr2("/foo");
+    json::json_pointer ptr3("/foo/0");
+
+    // call parent_pointer()
+    std::cout << std::boolalpha
+              << "parent of " << ptr1 << " is " << ptr1.parent_pointer() << '\n'
+              << "parent of " << ptr2 << " is " << ptr2.parent_pointer() << '\n'
+              << "parent of " << ptr3 << " is " << ptr3.parent_pointer() << std::endl;
+}

doc/examples/json_pointer__parent_pointer.link

+<a target="_blank" href="https://wandbox.org/permlink/yweqBQ8bAC6pcn68"><b>online</b></a>
\ No newline at end of file

doc/examples/json_pointer__parent_pointer.output

+parent of "" is ""
+parent of "/foo" is ""
+parent of "/foo/0" is "/foo"

doc/examples/json_pointer__pop_back.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create empty JSON Pointer
+    json::json_pointer ptr("/foo/bar/baz");
+    std::cout << ptr << '\n';
+
+    // call pop_back()
+    ptr.pop_back();
+    std::cout << ptr << '\n';
+
+    ptr.pop_back();
+    std::cout << ptr << '\n';
+
+    ptr.pop_back();
+    std::cout << ptr << '\n';
+}

doc/examples/json_pointer__pop_back.link

+<a target="_blank" href="https://wandbox.org/permlink/aFuDbxgbraVszcBX"><b>online</b></a>
\ No newline at end of file

doc/examples/json_pointer__pop_back.output

+"/foo/bar/baz"
+"/foo/bar"
+"/foo"
+""

doc/examples/json_pointer__push_back.cpp

+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create empty JSON Pointer
+    json::json_pointer ptr;
+    std::cout << ptr << '\n';
+
+    // call push_back()
+    ptr.push_back("foo");
+    std::cout << ptr << '\n';
+
+    ptr.push_back("0");
+    std::cout << ptr << '\n';
+
+    ptr.push_back("bar");
+    std::cout << ptr << '\n';
+}

doc/examples/json_pointer__push_back.link

+<a target="_blank" href="https://wandbox.org/permlink/kLC7IUvqQ6XJCeG9"><b>online</b></a>
\ No newline at end of file

doc/examples/json_pointer__push_back.output

+""
+"/foo"
+"/foo/0"
+"/foo/0/bar"

doc/examples/meta.output

@@ -2,7 +2,7 @@
     "compiler": {
         "c++": "201103",
         "family": "clang",
-        "version": "10.0.0 (clang-1000.11.45.5)"
+        "version": "11.0.0 (clang-1100.0.33.8)"
     },
     "copyright": "(C) 2013-2017 Niels Lohmann",
     "name": "JSON for Modern C++",
@@ -10,8 +10,8 @@
     "url": "https://github.com/nlohmann/json",
     "version": {
         "major": 3,
-        "minor": 5,
-        "patch": 0,
-        "string": "3.5.0"
+        "minor": 7,
+        "patch": 1,
+        "string": "3.7.1"
     }
 }

doc/index.md

@@ -4,7 +4,9 @@ These pages contain the API documentation of JSON for Modern C++, a C++11 header
 
 # Contents
 
-- @link nlohmann::basic_json `basic_json` class @endlink
+- Classes
+  - @link nlohmann::basic_json `basic_json`@endlink -- class template for JSON values
+  - @link nlohmann::json `json`@endlink -- the default specialization of `basic_json`, defined as `basic_json<>`
 - [Functions](functions_func.html)
   - object inspection
     - @link nlohmann::basic_json::dump dump @endlink -- value serialization
@@ -35,6 +37,12 @@ These pages contain the API documentation of JSON for Modern C++, a C++11 header
     - @link nlohmann::basic_json::out_of_range out_of_range @endlink for exceptions indicating access out of the defined range
     - @link nlohmann::basic_json::other_error other_error @endlink for exceptions indicating other library errors
   - lexicographical comparison operators
+    - @link nlohmann::basic_json::operator== operator== @endlink
+    - @link nlohmann::basic_json::operator!= operator!= @endlink
+    - @link nlohmann::basic_json::operator< operator<= @endlink
+    - @link nlohmann::basic_json::operator<= operator< @endlink
+    - @link nlohmann::basic_json::operator> operator> @endlink
+    - @link nlohmann::basic_json::operator>= operator>= @endlink
   - serialization
     - @link nlohmann::basic_json::dump dump @endlink serialize to string
     - @link nlohmann::basic_json::operator<<(std::ostream&, const basic_json &) operator<< @endlink serialize to stream
@@ -44,10 +52,12 @@ These pages contain the API documentation of JSON for Modern C++, a C++11 header
     - @link nlohmann::basic_json::operator>>(std::istream&, basic_json&) operator>> @endlink parse from stream
     - @link nlohmann::basic_json::accept accept @endlink check for syntax errors without parsing
     - @link nlohmann::json_sax SAX interface @endlink define a user-defined SAX event consumer
+    - @link nlohmann::basic_json::parser_callback_t callback interface @endlink register a callback to the parse function
   - [binary formats](binary_formats.md):
     - CBOR: @link nlohmann::basic_json::from_cbor from_cbor @endlink / @link nlohmann::basic_json::to_cbor to_cbor @endlink
     - MessagePack: @link nlohmann::basic_json::from_msgpack from_msgpack @endlink / @link nlohmann::basic_json::to_msgpack to_msgpack @endlink
     - UBJSON: @link nlohmann::basic_json::from_ubjson from_ubjson @endlink / @link nlohmann::basic_json::to_ubjson to_ubjson @endlink
+    - BSON: @link nlohmann::basic_json::from_bson from_bson @endlink / @link nlohmann::basic_json::to_bson to_bson @endlink
 - Types
   - @link nlohmann::basic_json::array_t arrays @endlink
   - @link nlohmann::basic_json::object_t objects @endlink
@@ -57,6 +67,10 @@ These pages contain the API documentation of JSON for Modern C++, a C++11 header
     - @link nlohmann::basic_json::number_integer_t signed integers @endlink
     - @link nlohmann::basic_json::number_unsigned_t unsigned integers @endlink
     - @link nlohmann::basic_json::number_float_t floating-point @endlink
+- further JSON standards
+  - @link nlohmann::json_pointer JSON Pointer @endlink (REF 6901)
+  - @link nlohmann::basic_json::patch JSON Patch @endlink (RFC 6902)
+  - @link nlohmann::basic_json::merge_patch JSON Merge Patch @endlink (RFC 7396)
 
 # Container function overview
 
@@ -281,7 +295,7 @@ Note that this table only lists those exceptions thrown due to the type. For ins
     <td class="ok_green">@link nlohmann::basic_json::swap `swap` @endlink</td>
   </tr>
   <tr>
-    <td rowspan="2">lookup</td>
+    <td rowspan="3">lookup</td>
     <td>`find`</td>
     <td class="ok_green">@link nlohmann::basic_json::find `find` @endlink</td>
     <td class="ok_green">@link nlohmann::basic_json::find `find` @endlink (returns `end()`)</td>
@@ -299,11 +313,20 @@ Note that this table only lists those exceptions thrown due to the type. For ins
     <td class="ok_green">@link nlohmann::basic_json::count `count` @endlink (returns `0`)</td>
     <td class="ok_green">@link nlohmann::basic_json::count `count` @endlink (returns `0`)</td>
   </tr>
+  <tr>
+    <td>`contains`</td>
+    <td class="ok_green">@link nlohmann::basic_json::contains `contains` @endlink</td>
+    <td class="ok_green">@link nlohmann::basic_json::contains `contains` @endlink (returns `false`)</td>
+    <td class="ok_green">@link nlohmann::basic_json::contains `contains` @endlink (returns `false`)</td>
+    <td class="ok_green">@link nlohmann::basic_json::contains `contains` @endlink (returns `false`)</td>
+    <td class="ok_green">@link nlohmann::basic_json::contains `contains` @endlink (returns `false`)</td>
+    <td class="ok_green">@link nlohmann::basic_json::contains `contains` @endlink (returns `false`)</td>
+  </tr>
 </table>
 
-@copyright Copyright &copy; 2013-2018 Niels Lohmann. The code is licensed under the [MIT License](http://opensource.org/licenses/MIT).
+@copyright Copyright &copy; 2013-2019 Niels Lohmann. The code is licensed under the [MIT License](http://opensource.org/licenses/MIT).
 
 @author [Niels Lohmann](http://nlohmann.me)
 @see https://github.com/nlohmann/json to download the source code
 
-@version 3.5.0
+@version 3.7.1

include/nlohmann/detail/conversions/from_json.hpp

@@ -26,7 +26,7 @@ namespace detail
 template<typename BasicJsonType>
 void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
 {
-    if (JSON_UNLIKELY(not j.is_null()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_null()))
     {
         JSON_THROW(type_error::create(302, "type must be null, but is " + std::string(j.type_name())));
     }
@@ -66,7 +66,7 @@ void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
 template<typename BasicJsonType>
 void from_json(const BasicJsonType& j, typename BasicJsonType::boolean_t& b)
 {
-    if (JSON_UNLIKELY(not j.is_boolean()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_boolean()))
     {
         JSON_THROW(type_error::create(302, "type must be boolean, but is " + std::string(j.type_name())));
     }
@@ -76,7 +76,7 @@ void from_json(const BasicJsonType& j, typename BasicJsonType::boolean_t& b)
 template<typename BasicJsonType>
 void from_json(const BasicJsonType& j, typename BasicJsonType::string_t& s)
 {
-    if (JSON_UNLIKELY(not j.is_string()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_string()))
     {
         JSON_THROW(type_error::create(302, "type must be string, but is " + std::string(j.type_name())));
     }
@@ -92,7 +92,7 @@ template <
         int > = 0 >
 void from_json(const BasicJsonType& j, ConstructibleStringType& s)
 {
-    if (JSON_UNLIKELY(not j.is_string()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_string()))
     {
         JSON_THROW(type_error::create(302, "type must be string, but is " + std::string(j.type_name())));
     }
@@ -132,10 +132,11 @@ template<typename BasicJsonType, typename T, typename Allocator,
          enable_if_t<std::is_convertible<BasicJsonType, T>::value, int> = 0>
 void from_json(const BasicJsonType& j, std::forward_list<T, Allocator>& l)
 {
-    if (JSON_UNLIKELY(not j.is_array()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_array()))
     {
         JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
     }
+    l.clear();
     std::transform(j.rbegin(), j.rend(),
                    std::front_inserter(l), [](const BasicJsonType & i)
     {
@@ -148,12 +149,22 @@ template<typename BasicJsonType, typename T,
          enable_if_t<std::is_convertible<BasicJsonType, T>::value, int> = 0>
 void from_json(const BasicJsonType& j, std::valarray<T>& l)
 {
-    if (JSON_UNLIKELY(not j.is_array()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_array()))
     {
         JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
     }
     l.resize(j.size());
-    std::copy(j.m_value.array->begin(), j.m_value.array->end(), std::begin(l));
+    std::copy(j.begin(), j.end(), std::begin(l));
+}
+
+template <typename BasicJsonType, typename T, std::size_t N>
+auto from_json(const BasicJsonType& j, T (&arr)[N])
+-> decltype(j.template get<T>(), void())
+{
+    for (std::size_t i = 0; i < N; ++i)
+    {
+        arr[i] = j.at(i).template get<T>();
+    }
 }
 
 template<typename BasicJsonType>
@@ -182,14 +193,16 @@ auto from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr, p
 {
     using std::end;
 
-    arr.reserve(j.size());
+    ConstructibleArrayType ret;
+    ret.reserve(j.size());
     std::transform(j.begin(), j.end(),
-                   std::inserter(arr, end(arr)), [](const BasicJsonType & i)
+                   std::inserter(ret, end(ret)), [](const BasicJsonType & i)
     {
         // get<BasicJsonType>() returns *this, this won't call a from_json
         // method when value_type is BasicJsonType
         return i.template get<typename ConstructibleArrayType::value_type>();
     });
+    arr = std::move(ret);
 }
 
 template <typename BasicJsonType, typename ConstructibleArrayType>
@@ -198,14 +211,16 @@ void from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr,
 {
     using std::end;
 
+    ConstructibleArrayType ret;
     std::transform(
-        j.begin(), j.end(), std::inserter(arr, end(arr)),
+        j.begin(), j.end(), std::inserter(ret, end(ret)),
         [](const BasicJsonType & i)
     {
         // get<BasicJsonType>() returns *this, this won't call a from_json
         // method when value_type is BasicJsonType
         return i.template get<typename ConstructibleArrayType::value_type>();
     });
+    arr = std::move(ret);
 }
 
 template <typename BasicJsonType, typename ConstructibleArrayType,
@@ -221,7 +236,7 @@ auto from_json(const BasicJsonType& j, ConstructibleArrayType& arr)
 j.template get<typename ConstructibleArrayType::value_type>(),
 void())
 {
-    if (JSON_UNLIKELY(not j.is_array()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_array()))
     {
         JSON_THROW(type_error::create(302, "type must be array, but is " +
                                       std::string(j.type_name())));
@@ -234,20 +249,22 @@ template<typename BasicJsonType, typename ConstructibleObjectType,
          enable_if_t<is_constructible_object_type<BasicJsonType, ConstructibleObjectType>::value, int> = 0>
 void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
 {
-    if (JSON_UNLIKELY(not j.is_object()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_object()))
     {
         JSON_THROW(type_error::create(302, "type must be object, but is " + std::string(j.type_name())));
     }
 
+    ConstructibleObjectType ret;
     auto inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
     using value_type = typename ConstructibleObjectType::value_type;
     std::transform(
         inner_object->begin(), inner_object->end(),
-        std::inserter(obj, obj.begin()),
+        std::inserter(ret, ret.begin()),
         [](typename BasicJsonType::object_t::value_type const & p)
     {
         return value_type(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>());
     });
+    obj = std::move(ret);
 }
 
 // overload for arithmetic types, not chosen for basic_json template arguments
@@ -315,13 +332,14 @@ template <typename BasicJsonType, typename Key, typename Value, typename Compare
                                      typename BasicJsonType::string_t, Key>::value>>
 void from_json(const BasicJsonType& j, std::map<Key, Value, Compare, Allocator>& m)
 {
-    if (JSON_UNLIKELY(not j.is_array()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_array()))
     {
         JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
     }
+    m.clear();
     for (const auto& p : j)
     {
-        if (JSON_UNLIKELY(not p.is_array()))
+        if (JSON_HEDLEY_UNLIKELY(not p.is_array()))
         {
             JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(p.type_name())));
         }
@@ -334,13 +352,14 @@ template <typename BasicJsonType, typename Key, typename Value, typename Hash, t
                                      typename BasicJsonType::string_t, Key>::value>>
 void from_json(const BasicJsonType& j, std::unordered_map<Key, Value, Hash, KeyEqual, Allocator>& m)
 {
-    if (JSON_UNLIKELY(not j.is_array()))
+    if (JSON_HEDLEY_UNLIKELY(not j.is_array()))
     {
         JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
     }
+    m.clear();
     for (const auto& p : j)
     {
-        if (JSON_UNLIKELY(not p.is_array()))
+        if (JSON_HEDLEY_UNLIKELY(not p.is_array()))
         {
             JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(p.type_name())));
         }
@@ -367,4 +386,4 @@ namespace
 {
 constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::value;
 } // namespace
-}  // namespace nlohmann
+} // namespace nlohmann

include/nlohmann/detail/conversions/to_json.hpp

 #pragma once
 
+#include <algorithm> // copy
 #include <ciso646> // or, and, not
 #include <iterator> // begin, end
+#include <string> // string
 #include <tuple> // tuple, get
 #include <type_traits> // is_same, is_constructible, is_floating_point, is_enum, underlying_type
 #include <utility> // move, forward, declval, pair
 #include <valarray> // valarray
 #include <vector> // vector
 
+#include <nlohmann/detail/iterators/iteration_proxy.hpp>
 #include <nlohmann/detail/meta/cpp_future.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>
 #include <nlohmann/detail/value_t.hpp>
-#include <nlohmann/detail/iterators/iteration_proxy.hpp>
 
 namespace nlohmann
 {
@@ -152,7 +154,10 @@ struct external_constructor<value_t::array>
         j.m_type = value_t::array;
         j.m_value = value_t::array;
         j.m_value.array->resize(arr.size());
-        std::copy(std::begin(arr), std::end(arr), j.m_value.array->begin());
+        if (arr.size() > 0)
+        {
+            std::copy(std::begin(arr), std::end(arr), j.m_value.array->begin());
+        }
         j.assert_invariant();
     }
 };
@@ -297,8 +302,8 @@ void to_json(BasicJsonType& j, const T(&arr)[N])
     external_constructor<value_t::array>::construct(j, arr);
 }
 
-template<typename BasicJsonType, typename... Args>
-void to_json(BasicJsonType& j, const std::pair<Args...>& p)
+template < typename BasicJsonType, typename T1, typename T2, enable_if_t < std::is_constructible<BasicJsonType, T1>::value&& std::is_constructible<BasicJsonType, T2>::value, int > = 0 >
+void to_json(BasicJsonType& j, const std::pair<T1, T2>& p)
 {
     j = { p.first, p.second };
 }
@@ -317,10 +322,10 @@ void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<Idx...>
     j = { std::get<Idx>(t)... };
 }
 
-template<typename BasicJsonType, typename... Args>
-void to_json(BasicJsonType& j, const std::tuple<Args...>& t)
+template<typename BasicJsonType, typename T, enable_if_t<is_constructible_tuple<BasicJsonType, T>::value, int > = 0>
+void to_json(BasicJsonType& j, const T& t)
 {
-    to_json_tuple_impl(j, t, index_sequence_for<Args...> {});
+    to_json_tuple_impl(j, t, make_index_sequence<std::tuple_size<T>::value> {});
 }
 
 struct to_json_fn
@@ -339,4 +344,4 @@ namespace
 {
 constexpr const auto& to_json = detail::static_const<detail::to_json_fn>::value;
 } // namespace
-}  // namespace nlohmann
+} // namespace nlohmann

include/nlohmann/detail/exceptions.hpp

@@ -5,6 +5,7 @@
 #include <string> // to_string
 
 #include <nlohmann/detail/input/position_t.hpp>
+#include <nlohmann/detail/macro_scope.hpp>
 
 namespace nlohmann
 {
@@ -46,6 +47,7 @@ class exception : public std::exception
 {
   public:
     /// returns the explanatory string
+    JSON_HEDLEY_RETURNS_NON_NULL
     const char* what() const noexcept override
     {
         return m.what();
@@ -55,6 +57,7 @@ class exception : public std::exception
     const int id;
 
   protected:
+    JSON_HEDLEY_NON_NULL(3)
     exception(int id_, const char* what_arg) : id(id_), m(what_arg) {}
 
     static std::string name(const std::string& ename, int id_)
@@ -102,12 +105,12 @@ json.exception.parse_error.114 | parse error: Unsupported BSON record type 0x0F
 @liveexample{The following code shows how a `parse_error` exception can be
 caught.,parse_error}
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref invalid_iterator for exceptions indicating errors with iterators
-@sa @ref type_error for exceptions indicating executing a member function with
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref invalid_iterator for exceptions indicating errors with iterators
+@sa - @ref type_error for exceptions indicating executing a member function with
                     a wrong type
-@sa @ref out_of_range for exceptions indicating access out of the defined range
-@sa @ref other_error for exceptions indicating other library errors
+@sa - @ref out_of_range for exceptions indicating access out of the defined range
+@sa - @ref other_error for exceptions indicating other library errors
 
 @since version 3.0.0
 */
@@ -117,7 +120,7 @@ class parse_error : public exception
     /*!
     @brief create a parse error exception
     @param[in] id_       the id of the exception
-    @param[in] position  the position where the error occurred (or with
+    @param[in] pos       the position where the error occurred (or with
                          chars_read_total=0 if the position cannot be
                          determined)
     @param[in] what_arg  the explanatory string
@@ -188,12 +191,12 @@ json.exception.invalid_iterator.214 | cannot get value | Cannot get value for it
 @liveexample{The following code shows how an `invalid_iterator` exception can be
 caught.,invalid_iterator}
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref parse_error for exceptions indicating a parse error
-@sa @ref type_error for exceptions indicating executing a member function with
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref parse_error for exceptions indicating a parse error
+@sa - @ref type_error for exceptions indicating executing a member function with
                     a wrong type
-@sa @ref out_of_range for exceptions indicating access out of the defined range
-@sa @ref other_error for exceptions indicating other library errors
+@sa - @ref out_of_range for exceptions indicating access out of the defined range
+@sa - @ref other_error for exceptions indicating other library errors
 
 @since version 3.0.0
 */
@@ -207,6 +210,7 @@ class invalid_iterator : public exception
     }
 
   private:
+    JSON_HEDLEY_NON_NULL(3)
     invalid_iterator(int id_, const char* what_arg)
         : exception(id_, what_arg) {}
 };
@@ -223,7 +227,7 @@ name / id                     | example message | description
 ----------------------------- | --------------- | -------------------------
 json.exception.type_error.301 | cannot create object from initializer list | To create an object from an initializer list, the initializer list must consist only of a list of pairs whose first element is a string. When this constraint is violated, an array is created instead.
 json.exception.type_error.302 | type must be object, but is array | During implicit or explicit value conversion, the JSON type must be compatible to the target type. For instance, a JSON string can only be converted into string types, but not into numbers or boolean types.
-json.exception.type_error.303 | incompatible ReferenceType for get_ref, actual type is object | To retrieve a reference to a value stored in a @ref basic_json object with @ref get_ref, the type of the reference must match the value type. For instance, for a JSON array, the @a ReferenceType must be @ref array_t&.
+json.exception.type_error.303 | incompatible ReferenceType for get_ref, actual type is object | To retrieve a reference to a value stored in a @ref basic_json object with @ref get_ref, the type of the reference must match the value type. For instance, for a JSON array, the @a ReferenceType must be @ref array_t &.
 json.exception.type_error.304 | cannot use at() with string | The @ref at() member functions can only be executed for certain JSON types.
 json.exception.type_error.305 | cannot use operator[] with string | The @ref operator[] member functions can only be executed for certain JSON types.
 json.exception.type_error.306 | cannot use value() with string | The @ref value() member functions can only be executed for certain JSON types.
@@ -242,11 +246,11 @@ json.exception.type_error.317 | JSON value cannot be serialized to requested for
 @liveexample{The following code shows how a `type_error` exception can be
 caught.,type_error}
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref parse_error for exceptions indicating a parse error
-@sa @ref invalid_iterator for exceptions indicating errors with iterators
-@sa @ref out_of_range for exceptions indicating access out of the defined range
-@sa @ref other_error for exceptions indicating other library errors
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref parse_error for exceptions indicating a parse error
+@sa - @ref invalid_iterator for exceptions indicating errors with iterators
+@sa - @ref out_of_range for exceptions indicating access out of the defined range
+@sa - @ref other_error for exceptions indicating other library errors
 
 @since version 3.0.0
 */
@@ -260,6 +264,7 @@ class type_error : public exception
     }
 
   private:
+    JSON_HEDLEY_NON_NULL(3)
     type_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
 };
 
@@ -287,12 +292,12 @@ json.exception.out_of_range.409 | BSON key cannot contain code point U+0000 (at
 @liveexample{The following code shows how an `out_of_range` exception can be
 caught.,out_of_range}
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref parse_error for exceptions indicating a parse error
-@sa @ref invalid_iterator for exceptions indicating errors with iterators
-@sa @ref type_error for exceptions indicating executing a member function with
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref parse_error for exceptions indicating a parse error
+@sa - @ref invalid_iterator for exceptions indicating errors with iterators
+@sa - @ref type_error for exceptions indicating executing a member function with
                     a wrong type
-@sa @ref other_error for exceptions indicating other library errors
+@sa - @ref other_error for exceptions indicating other library errors
 
 @since version 3.0.0
 */
@@ -306,6 +311,7 @@ class out_of_range : public exception
     }
 
   private:
+    JSON_HEDLEY_NON_NULL(3)
     out_of_range(int id_, const char* what_arg) : exception(id_, what_arg) {}
 };
 
@@ -321,12 +327,12 @@ name / id                      | example message | description
 ------------------------------ | --------------- | -------------------------
 json.exception.other_error.501 | unsuccessful: {"op":"test","path":"/baz", "value":"bar"} | A JSON Patch operation 'test' failed. The unsuccessful operation is also printed.
 
-@sa @ref exception for the base class of the library exceptions
-@sa @ref parse_error for exceptions indicating a parse error
-@sa @ref invalid_iterator for exceptions indicating errors with iterators
-@sa @ref type_error for exceptions indicating executing a member function with
+@sa - @ref exception for the base class of the library exceptions
+@sa - @ref parse_error for exceptions indicating a parse error
+@sa - @ref invalid_iterator for exceptions indicating errors with iterators
+@sa - @ref type_error for exceptions indicating executing a member function with
                     a wrong type
-@sa @ref out_of_range for exceptions indicating access out of the defined range
+@sa - @ref out_of_range for exceptions indicating access out of the defined range
 
 @liveexample{The following code shows how an `other_error` exception can be
 caught.,other_error}
@@ -343,6 +349,7 @@ class other_error : public exception
     }
 
   private:
+    JSON_HEDLEY_NON_NULL(3)
     other_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
 };
 }  // namespace detail

include/nlohmann/detail/input/position_t.hpp

@@ -23,5 +23,5 @@ struct position_t
     }
 };
 
-}
-}
+} // namespace detail
+} // namespace nlohmann

include/nlohmann/detail/iterators/iter_impl.hpp

@@ -118,17 +118,42 @@ class iter_impl
           to iterator is not defined.
     */
 
+    /*!
+    @brief const copy constructor
+    @param[in] other const iterator to copy from
+    @note This copy constructor had to be defined explicitly to circumvent a bug
+          occurring on msvc v19.0 compiler (VS 2015) debug build. For more
+          information refer to: https://github.com/nlohmann/json/issues/1608
+    */
+    iter_impl(const iter_impl<const BasicJsonType>& other) noexcept
+        : m_object(other.m_object), m_it(other.m_it)
+    {}
+
+    /*!
+    @brief converting assignment
+    @param[in] other const iterator to copy from
+    @return const/non-const iterator
+    @note It is not checked whether @a other is initialized.
+    */
+    iter_impl& operator=(const iter_impl<const BasicJsonType>& other) noexcept
+    {
+        m_object = other.m_object;
+        m_it = other.m_it;
+        return *this;
+    }
+
     /*!
     @brief converting constructor
     @param[in] other  non-const iterator to copy from
     @note It is not checked whether @a other is initialized.
     */
     iter_impl(const iter_impl<typename std::remove_const<BasicJsonType>::type>& other) noexcept
-        : m_object(other.m_object), m_it(other.m_it) {}
+        : m_object(other.m_object), m_it(other.m_it)
+    {}
 
     /*!
     @brief converting assignment
-    @param[in,out] other  non-const iterator to copy from
+    @param[in] other  non-const iterator to copy from
     @return const/non-const iterator
     @note It is not checked whether @a other is initialized.
     */
@@ -235,7 +260,7 @@ class iter_impl
 
             default:
             {
-                if (JSON_LIKELY(m_it.primitive_iterator.is_begin()))
+                if (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.is_begin()))
                 {
                     return *m_object;
                 }
@@ -269,7 +294,7 @@ class iter_impl
 
             default:
             {
-                if (JSON_LIKELY(m_it.primitive_iterator.is_begin()))
+                if (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.is_begin()))
                 {
                     return m_object;
                 }
@@ -372,7 +397,7 @@ class iter_impl
     bool operator==(const iter_impl& other) const
     {
         // if objects are not the same, the comparison is undefined
-        if (JSON_UNLIKELY(m_object != other.m_object))
+        if (JSON_HEDLEY_UNLIKELY(m_object != other.m_object))
         {
             JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
         }
@@ -408,7 +433,7 @@ class iter_impl
     bool operator<(const iter_impl& other) const
     {
         // if objects are not the same, the comparison is undefined
-        if (JSON_UNLIKELY(m_object != other.m_object))
+        if (JSON_HEDLEY_UNLIKELY(m_object != other.m_object))
         {
             JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers"));
         }
@@ -568,7 +593,7 @@ class iter_impl
 
             default:
             {
-                if (JSON_LIKELY(m_it.primitive_iterator.get_value() == -n))
+                if (JSON_HEDLEY_LIKELY(m_it.primitive_iterator.get_value() == -n))
                 {
                     return *m_object;
                 }
@@ -586,7 +611,7 @@ class iter_impl
     {
         assert(m_object != nullptr);
 
-        if (JSON_LIKELY(m_object->is_object()))
+        if (JSON_HEDLEY_LIKELY(m_object->is_object()))
         {
             return m_it.object_iterator->first;
         }
@@ -607,7 +632,7 @@ class iter_impl
     /// associated JSON instance
     pointer m_object = nullptr;
     /// the actual iterator of the associated instance
-    internal_iterator<typename std::remove_const<BasicJsonType>::type> m_it;
+    internal_iterator<typename std::remove_const<BasicJsonType>::type> m_it {};
 };
-}  // namespace detail
-} // namespace nlohmann
\ No newline at end of file
+} // namespace detail
+} // namespace nlohmann

include/nlohmann/detail/iterators/iteration_proxy.hpp

 #pragma once
 
 #include <cstddef> // size_t
-#include <string> // string, to_string
 #include <iterator> // input_iterator_tag
+#include <string> // string, to_string
 #include <tuple> // tuple_size, get, tuple_element
 
-#include <nlohmann/detail/value_t.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>
+#include <nlohmann/detail/value_t.hpp>
 
 namespace nlohmann
 {
 namespace detail
 {
+template<typename string_type>
+void int_to_string( string_type& target, std::size_t value )
+{
+    target = std::to_string(value);
+}
 template <typename IteratorType> class iteration_proxy_value
 {
   public:
@@ -20,6 +25,7 @@ template <typename IteratorType> class iteration_proxy_value
     using pointer = value_type * ;
     using reference = value_type & ;
     using iterator_category = std::input_iterator_tag;
+    using string_type = typename std::remove_cv< typename std::remove_reference<decltype( std::declval<IteratorType>().key() ) >::type >::type;
 
   private:
     /// the iterator
@@ -29,9 +35,9 @@ template <typename IteratorType> class iteration_proxy_value
     /// last stringified array index
     mutable std::size_t array_index_last = 0;
     /// a string representation of the array index
-    mutable std::string array_index_str = "0";
+    mutable string_type array_index_str = "0";
     /// an empty string (to return a reference for primitive values)
-    const std::string empty_str = "";
+    const string_type empty_str = "";
 
   public:
     explicit iteration_proxy_value(IteratorType it) noexcept : anchor(it) {}
@@ -64,7 +70,7 @@ template <typename IteratorType> class iteration_proxy_value
     }
 
     /// return key of the iterator
-    const std::string& key() const
+    const string_type& key() const
     {
         assert(anchor.m_object != nullptr);
 
@@ -75,7 +81,7 @@ template <typename IteratorType> class iteration_proxy_value
             {
                 if (array_index != array_index_last)
                 {
-                    array_index_str = std::to_string(array_index);
+                    int_to_string( array_index_str, array_index );
                     array_index_last = array_index;
                 }
                 return array_index_str;
@@ -147,6 +153,11 @@ auto get(const nlohmann::detail::iteration_proxy_value<IteratorType>& i) -> decl
 // And see https://github.com/nlohmann/json/pull/1391
 namespace std
 {
+#if defined(__clang__)
+    // Fix: https://github.com/nlohmann/json/issues/1401
+    #pragma clang diagnostic push
+    #pragma clang diagnostic ignored "-Wmismatched-tags"
+#endif
 template <typename IteratorType>
 class tuple_size<::nlohmann::detail::iteration_proxy_value<IteratorType>>
             : public std::integral_constant<std::size_t, 2> {};
@@ -159,4 +170,7 @@ class tuple_element<N, ::nlohmann::detail::iteration_proxy_value<IteratorType >>
                      get<N>(std::declval <
                             ::nlohmann::detail::iteration_proxy_value<IteratorType >> ()));
 };
-}
\ No newline at end of file
+#if defined(__clang__)
+    #pragma clang diagnostic pop
+#endif
+} // namespace std

include/nlohmann/detail/value_t.hpp

@@ -4,6 +4,7 @@
 #include <ciso646> // and
 #include <cstddef> // size_t
 #include <cstdint> // uint8_t
+#include <string> // string
 
 namespace nlohmann
 {

test/src/UBSAN.supp

+unsigned-integer-overflow:stl_bvector.h