Merge remote-tracking branch 'origin/main' into final_action-revision

2024-11-03 17:56:43 -05:00 · 2022-09-26 15:27:01 -07:00 · 2022-09-26 15:27:01 -07:00 · 8840d87199
commit 8840d87199
parent d569ed65d0 10df83d292
42 changed files with 1696 additions and 1720 deletions
--- a/.github/workflows/android.yml
+++ b/.github/workflows/android.yml
@ -29,7 +29,7 @@ jobs:
          echo "Emulator starting"

      - name: Configure
-        run: cmake -Werror=dev -DCMAKE_TOOLCHAIN_FILE=$ANDROID_HOME/ndk-bundle/build/cmake/android.toolchain.cmake -DANDROID_PLATFORM=16 -DANDROID_ABI=x86_64 -DCMAKE_BUILD_TYPE=Debug ..
+        run: cmake -Werror=dev -DCMAKE_TOOLCHAIN_FILE=$ANDROID_HOME/ndk/25.0.8775105/build/cmake/android.toolchain.cmake -DANDROID_PLATFORM=16 -DANDROID_ABI=x86_64 -DCMAKE_BUILD_TYPE=Debug ..

      - name: Build
        run: cmake --build . --parallel
--- a/.github/workflows/ios.yml
+++ b/.github/workflows/ios.yml
@ -25,11 +25,11 @@ jobs:
            -GXcode \
            -DCMAKE_SYSTEM_NAME=iOS \
            "-DCMAKE_OSX_ARCHITECTURES=arm64;x86_64" \
-            -DCMAKE_OSX_DEPLOYMENT_TARGET=8 \
+            -DCMAKE_OSX_DEPLOYMENT_TARGET=9 \
            -DCMAKE_TRY_COMPILE_TARGET_TYPE=STATIC_LIBRARY \
            "-DMACOSX_BUNDLE_GUI_IDENTIFIER=GSL.\$(EXECUTABLE_NAME)" \
-            -DMACOSX_BUNDLE_BUNDLE_VERSION=3.0.1 \
-            -DMACOSX_BUNDLE_SHORT_VERSION_STRING=3.0.1 \
+            -DMACOSX_BUNDLE_BUNDLE_VERSION=3.1.0 \
+            -DMACOSX_BUNDLE_SHORT_VERSION_STRING=3.1.0 \
            ..

      - name: Build
--- a/.travis.yml
+++ b/.travis.yml
@ -1,337 +0,0 @@
-
-language: cpp
-notifications:
-  email: false
-
-# Use Linux unless specified otherwise
-os: linux
-dist: bionic
-
-cache:
-  directories:
-    - ${TRAVIS_BUILD_DIR}/deps
-
-stages:
-  - name: Latest     # Compiler with the latest major version
-  - name: Previous   # Compilers with the major version Latest - 1
-  - name: Validation # run other jobs
-
-jobs:
-  include:
-
-    ##########################################################################
-    # Validate CMake configuration
-    ##########################################################################
-
-    - name: CMake 3.1.3 - latest
-      stage: Validation
-      env: &CMAKE_VERSION_LIST
-      - CMAKE_VERSION: '"3.17.0 3.16.5 3.15.7 3.14.7 3.13.5 3.12.4 3.11.4 3.10.3 3.9.6 3.8.2 3.7.2 3.6.3 3.5.2 3.4.3 3.3.2 3.2.3 3.1.3"'
-      - GSL_CXX_STANDARD: 14
-      addons: # Get latest release (candidate)
-        apt:
-          sources:
-          - sourceline: 'deb https://apt.kitware.com/ubuntu/ bionic main'
-            key_url: 'https://apt.kitware.com/keys/kitware-archive-latest.asc'
-          - sourceline: 'deb https://apt.kitware.com/ubuntu/ bionic-rc main'
-          packages:
-          - cmake
-      script:
-      - |
-        cd ./build
-        ( set -eu
-          for CMAKE in ${CMAKE_path[@]}; do test_CMake_generate $CMAKE; done
-          export CXX=clang++
-          for CMAKE in ${CMAKE_path[@]}; do test_CMake_generate $CMAKE; done
-        )
-
-    - name: CMake 3.2.3 - 3.17.0
-      stage: Validation
-      os: osx
-      osx_image: xcode11.3
-      env:
-      - CMAKE_VERSION: '"3.17.0 3.16.5 3.15.7 3.14.7 3.13.5 3.12.4 3.11.4 3.10.3 3.9.6 3.8.2 3.7.2 3.6.3 3.5.2 3.4.3 3.3.2 3.2.3"'
-      script:
-      - |
-        cd ./build
-        ( set -eu
-          for CMAKE in ${CMAKE_path[@]}; do test_CMake_generate $CMAKE; done
-        )
-
-    ##########################################################################
-    # AppleClang on OSX
-    ##########################################################################
-
-
-
-    # Xcode 10.3
-    - name: AppleClang Xcode-10.3 C++14 Debug
-      stage: Previous
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode10.3 # AppleClang 10.0.1 same compiler as Xcode 10.2
-    - name: AppleClang Xcode-10.3 C++14 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode10.3
-    - name: AppleClang Xcode-10.3 C++17 Debug
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode10.3
-    - name: AppleClang Xcode-10.3 C++17 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode10.3
-
-
-    # Xcode 11.4
-    - name: AppleClang Xcode-11.4 C++17 Debug
-      stage: Latest
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode11.4
-    - name: AppleClang Xcode-11.4 C++17 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode11.4
-    - name: AppleClang Xcode-11.4 C++14 Debug
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode11.4
-    - name: AppleClang Xcode-11.4 C++14 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode11.4
-
-    ##########################################################################
-    # Clang on Linux
-    ##########################################################################
-
-    # Clang 9
-    - name: Clang-9 C++14 Debug
-      stage: Previous
-      env: CXX=clang++-9 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang9
-        apt:
-          sources:
-          - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main'
-            key_url: https://apt.llvm.org/llvm-snapshot.gpg.key
-          packages:
-          - clang-9
-    - name: Clang-9 C++14 Release
-      env: CXX=clang++-9 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang9
-    - name: Clang-9 C++17 Debug
-      env: CXX=clang++-9 BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      addons: *clang9
-    - name: Clang-9 C++17 Release
-      env: CXX=clang++-9 BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      addons: *clang9
-
-    # Clang 10
-    - name: Clang-10 C++14 Debug
-      stage: Latest
-      env: CXX=clang++-10 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang10
-        apt:
-          sources:
-          - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-10 main'
-            key_url: https://apt.llvm.org/llvm-snapshot.gpg.key
-          packages:
-          - clang-10
-    - name: Clang-10 C++14 Release
-      env: CXX=clang++-10 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang10
-    - name: Clang-10 C++17 Debug
-      env: CXX=clang++-10 BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      addons: *clang10
-    - name: Clang-10 C++17 Release
-      env: CXX=clang++-10 BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      addons: *clang10
-
-    ##########################################################################
-    # GCC on Linux
-    ##########################################################################
-
-    # GCC 8
-    - name: GCC-8 C++14 Debug
-      stage: Previous
-      env: CXX=g++-8 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &gcc8
-        apt:
-          packages: g++-8
-    - name: GCC-8 C++14 Release
-      env: CXX=g++-8 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *gcc8
-    - name: GCC-8 C++17 Debug
-      env: CXX=g++-8 BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      addons: *gcc8
-    - name: GCC-8 C++17 Release
-      env: CXX=g++-8 BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      addons: *gcc8
-
-    # GCC 9
-    - name: GCC-9 C++14 Debug
-      stage: Latest
-      env: CXX=g++-9 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &gcc9
-        apt:
-          sources:
-          - sourceline: ppa:ubuntu-toolchain-r/test
-          packages:
-          - g++-9
-    - name: GCC-9 C++14 Release
-      env: CXX=g++-9 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *gcc9
-    - name: GCC-9 C++17 Debug
-      env: CXX=g++-9 BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      addons: *gcc9
-    - name: GCC-9 C++17 Release
-      env: CXX=g++-9 BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      addons: *gcc9
-
-before_install:
-  - |
-    # Configuration
-    JOBS=2 # Travis machines have 2 cores
-    # Dependencies required by the CI (cached directory)
-    DEPS_DIR="${TRAVIS_BUILD_DIR}/deps"
-  - |
-    # Setup
-    mkdir -p "${DEPS_DIR:?}" && cd "${DEPS_DIR:?}"
-    mkdir -p ~/tools && cd ~/tools
-    if [[ ${TRAVIS_OS_NAME:?} == "osx" ]]; then
-      export PATH="/usr/local/opt/coreutils/libexec/gnubin:$PATH"
-    fi
-  - |
-    # Helper functions
-    # usage: if [[ $(check_url '<url>') ]]; then ...
-    function check_url {( set +e
-      if [[ "$1" =~ 'github.com' ]]; then # check for first byte
-        if curl --fail --silent --output /dev/null --connect-timeout 12 --range 0-0 "$1"
-        then echo true; fi
-      else # request head
-        if curl --fail --silent --output /dev/null --connect-timeout 12 --head "$1"
-        then echo true; fi
-      fi
-      return
-    )}
-
-install:
-  ############################################################################
-  # Install a different CMake version (or several)
-  ############################################################################
-  - |
-    # Install CMake versions
-    ( set -euo pipefail
-      if [[ ${CMAKE_VERSION:-} ]]; then
-        if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
-          OS="Linux"; EXT="sh"
-          if [[ ! ("${CMAKE_VERSION:-}" =~ .+[' '].+) ]]; then
-            # Single entry -> default CMake version
-            CMAKE_DEFAULT_DIR="/usr/local"
-          fi
-        elif [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then OS="Darwin"; EXT="tar.gz"
-        else echo "CMake install not supported for this OS."; exit 1
-        fi
-        CMAKE_INSTALLER="install-cmake.${EXT}"
-      fi
-      for VERSION in ${CMAKE_VERSION:-}; do
-        CMAKE_URL="https://github.com/Kitware/CMake/releases/download/v${VERSION}/cmake-${VERSION}-${OS}-x86_64.${EXT}"
-        if [[ $(check_url "$CMAKE_URL") ]]; then
-          curl -sSL ${CMAKE_URL} -o ${CMAKE_INSTALLER}
-          CMAKE_DIR="${CMAKE_DEFAULT_DIR:-"${HOME}/tools/cmake-${VERSION}"}"
-          mkdir -p ${CMAKE_DIR}
-          if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
-            chmod +x ${CMAKE_INSTALLER}
-            sudo ./${CMAKE_INSTALLER} --prefix=${CMAKE_DIR} --skip-license
-          else # OSX
-            mkdir -p ./CMake_tmp
-            tar --extract --gzip --file=${CMAKE_INSTALLER} --directory=./CMake_tmp
-            mv ./CMake_tmp/*/CMake.app/Contents/* ${CMAKE_DIR}
-          fi
-          rm --recursive --force ./CMake_tmp ${CMAKE_INSTALLER}
-        else echo 'Invalid url!'; echo "Version: ${VERSION}"
-        fi
-      done
-    )
-    if [[ ${CMAKE_VERSION:-} && "${TRAVIS_OS_NAME:?}" == "osx" && ! ("${CMAKE_VERSION:-}" =~ .+[' '].+) ]]
-    then # Single entry -> default CMake version
-      export PATH=${HOME}/tools/cmake-${CMAKE_VERSION:?}/bin:$PATH
-    fi
-    CMAKE_path=("cmake") # start with installed CMake version
-    for VERSION in ${CMAKE_VERSION:-}; do
-      tmp_path="$HOME/tools/cmake-${VERSION:?}/bin/cmake"
-      if [[ -x "$(command -v ${tmp_path:?})" ]]; then CMAKE_path+=("${tmp_path:?}"); fi
-    done
-    function test_CMake_generate {
-      # $1: cmake or full path to cmake
-      shopt -s extglob
-      if [[ "$1" == "cmake" || -x "$(command -v $1)" && "$1" =~ .*cmake$ ]]; then
-        echo "----------------"
-        $1 --version
-        echo "Configuration = ${BUILD_TYPE:-Debug}"
-        $1 -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} ${CMAKE_GEN_FLAGS[@]:?} ..
-        rm -rf !(tests/googletest-*)
-        if [[ ! ${BUILD_TYPE:-} ]]; then echo "" && echo "Configuration = Release"
-          $1 -DCMAKE_BUILD_TYPE=Release ${CMAKE_GEN_FLAGS[@]:?} ..
-          rm -rf !(tests/googletest-*)
-        fi
-      else echo "Non existing command: $1"
-      fi
-    }
-  - |
-    # CMake wrapper (Trusty, Xenial & Bionic); restore default behaviour.
-    if [[ "${TRAVIS_OS_NAME:?}" == "linux" &&
-          "$(lsb_release --codename)" =~ (trusty|xenial|bionic)$ ]]
-    then
-      if [[ -x $(command -v /usr/local/bin/cmake) ]]; then
-        function cmake { command /usr/local/bin/cmake $@; }
-      elif [[ -x $(command -v /usr/bin/cmake) ]]; then
-        function cmake { command /usr/bin/cmake $@; }
-      fi
-    fi
-
-  ############################################################################
-  # [linux]: Install the right version of libc++
-  # Based on https://github.com/ldionne/hana/blob/master/.travis.yml
-  ############################################################################
-  - |
-    LLVM_INSTALL=${DEPS_DIR:?}/llvm/install
-    # if in linux and compiler clang and llvm not installed
-    if [[ "${TRAVIS_OS_NAME:?}" == "linux" && "${CXX%%+*}" == "clang" && -n "$(ls -A ${LLVM_INSTALL:?})" ]]; then
-      if   [[ "${CXX}" == "clang++-3.6" ]]; then LLVM_VERSION="3.6.2";
-      elif [[ "${CXX}" == "clang++-3.7" ]]; then LLVM_VERSION="3.7.1";
-      elif [[ "${CXX}" == "clang++-3.8" ]]; then LLVM_VERSION="3.8.1";
-      elif [[ "${CXX}" == "clang++-3.9" ]]; then LLVM_VERSION="3.9.1";
-      fi
-      LLVM_URL="http://llvm.org/releases/${LLVM_VERSION}/llvm-${LLVM_VERSION}.src.tar.xz"
-      LIBCXX_URL="http://llvm.org/releases/${LLVM_VERSION}/libcxx-${LLVM_VERSION}.src.tar.xz"
-      LIBCXXABI_URL="http://llvm.org/releases/${LLVM_VERSION}/libcxxabi-${LLVM_VERSION}.src.tar.xz"
-      mkdir -p llvm llvm/build llvm/projects/libcxx llvm/projects/libcxxabi
-      travis_retry wget -O - ${LLVM_URL} | tar --strip-components=1 -xJ -C llvm
-      travis_retry wget -O - ${LIBCXX_URL} | tar --strip-components=1 -xJ -C llvm/projects/libcxx
-      travis_retry wget -O - ${LIBCXXABI_URL} | tar --strip-components=1 -xJ -C llvm/projects/libcxxabi
-      (cd llvm/build && cmake .. -DCMAKE_INSTALL_PREFIX=${LLVM_INSTALL})
-      (cd llvm/build/projects/libcxx && make install -j2)
-      (cd llvm/build/projects/libcxxabi && make install -j2)
-      export CXXFLAGS="-isystem ${LLVM_INSTALL}/include/c++/v1"
-      export LDFLAGS="-L ${LLVM_INSTALL}/lib -l c++ -l c++abi"
-      export LD_LIBRARY_PATH="${LD_LIBRARY_PATH}:${LLVM_INSTALL}/lib"
-    fi
-
-before_script:
-  - |
-    cd "${TRAVIS_BUILD_DIR:?}"
-    mkdir build && cd build
-    if [[ ${GSL_CXX_STANDARD:-} ]]; then
-      CMAKE_GEN_FLAGS=("-DGSL_CXX_STANDARD=$GSL_CXX_STANDARD")
-    fi
-    CMAKE_GEN_FLAGS+=("-Wdev -Werror=dev --warn-uninitialized")
-
-script:
-  # generate build files
-  - cmake .. -DCMAKE_BUILD_TYPE=${BUILD_TYPE:?} ${CMAKE_GEN_FLAGS[@]:?}
-  # build and run tests
-  - cmake --build . -- -j${JOBS}
-  - ctest --output-on-failure -j${JOBS}
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -4,7 +4,7 @@ list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/")
 include(guidelineSupportLibrary)

 project(GSL
-    VERSION 3.1.0
+    VERSION 4.0.0
    LANGUAGES CXX
 )

--- a/README.md
+++ b/README.md
@ -30,14 +30,14 @@ not_null                           | &#x2611;   | restricts a pointer / smart po
 span                               | &#x2611;   | a view over a contiguous sequence of memory. Based on the standardized verison of `std::span`, however `gsl::span` enforces bounds checking. See the [wiki](https://github.com/microsoft/GSL/wiki/gsl::span-and-std::span) for additional information.
 span_p                             | &#x2610;   | spans a range starting from a pointer to the first place for which the predicate is true
 basic_zstring                      | &#x2611;   | A pointer to a C-string (zero-terminated array) with a templated char type
-zstring                            | &#x2611;   | An alias to `basic_zstring` with a char type of char
-czstring                           | &#x2611;   | An alias to `basic_zstring` with a char type of const char
-wzstring                           | &#x2611;   | An alias to `basic_zstring` with a char type of wchar_t
-cwzstring                          | &#x2611;   | An alias to `basic_zstring` with a char type of const wchar_t
-u16zstring                         | &#x2611;   | An alias to `basic_zstring` with a char type of char16_t
-cu16zstring                        | &#x2611;   | An alias to `basic_zstring` with a char type of const char16_t
-u32zstring                         | &#x2611;   | An alias to `basic_zstring` with a char type of char32_t
-cu32zstring                        | &#x2611;   | An alias to `basic_zstring` with a char type of const char32_t
+zstring                            | &#x2611;   | An alias to `basic_zstring` with dynamic extent and a char type of char
+czstring                           | &#x2611;   | An alias to `basic_zstring` with dynamic extent and a char type of const char
+wzstring                           | &#x2611;   | An alias to `basic_zstring` with dynamic extent and a char type of wchar_t
+cwzstring                          | &#x2611;   | An alias to `basic_zstring` with dynamic extent and a char type of const wchar_t
+u16zstring                         | &#x2611;   | An alias to `basic_zstring` with dynamic extent and a char type of char16_t
+cu16zstring                        | &#x2611;   | An alias to `basic_zstring` with dynamic extent and a char type of const char16_t
+u32zstring                         | &#x2611;   | An alias to `basic_zstring` with dynamic extent and a char type of char32_t
+cu32zstring                        | &#x2611;   | An alias to `basic_zstring` with dynamic extent and a char type of const char32_t
 [**2. Owners**][cg-owners]         |            |
 unique_ptr                         | &#x2611;   | an alias to `std::unique_ptr`
 shared_ptr                         | &#x2611;   | an alias to `std::shared_ptr`
@ -85,17 +85,25 @@ This is based on [CppCoreGuidelines semi-specification](https://github.com/isocp
 [cg-concepts]: https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#gslconcept-concepts

 # Quick Start
-## Supported Compilers
-The GSL officially supports the current and previous major release of MSVC, GCC, Clang, and XCode's Apple-Clang.
-See our latest test results for the most up-to-date list of supported configurations.
+## Supported Compilers / Toolsets
+The GSL officially supports the latest and previous major versions of VS with MSVC & LLVM, GCC, Clang, and XCode with Apple-Clang.
+Within these two major versions, we try to target the latest minor updates / revisions (although this may be affected by
+delays between a toolchain's release and when it becomes widely available for use).
+Below is a table showing the versions currently being tested.

 Compiler |Toolset Versions Currently Tested
 :------- |--:
- XCode |11.4 & 10.3
- GCC |9 & 8
- Clang |11 &  10
- Visual Studio with MSVC | VS2017 (15.9) & VS2019 (16.4) 
- Visual Studio with LLVM | VS2017 (Clang 9) & VS2019 (Clang 10)
+ XCode | 13.2.1 & 12.5.1
+ GCC | 11[^1] & 10[^2]
+ Clang | 12[^2] & 11[^2]
+ Visual Studio with MSVC | VS2022[^3] & VS2019[^4]
+ Visual Studio with LLVM | VS2022[^3] & VS2019[^4]
+
+
+[^1]: Precise version may be found in the [latest CI results](https://dev.azure.com/cppstat/GSL/_build?definitionId=1&branchFilter=26).
+[^2]: Precise version may be found in the [latest CI results](https://dev.azure.com/cppstat/GSL/_build?definitionId=1&branchFilter=26). Should be the version specified [here](https://github.com/actions/virtual-environments/blob/main/images/linux/Ubuntu2004-Readme.md#language-and-runtime).
+[^3]: Precise version may be found in the [latest CI results](https://dev.azure.com/cppstat/GSL/_build?definitionId=1&branchFilter=26). Should be the version specified [here](https://github.com/actions/virtual-environments/blob/main/images/win/Windows2022-Readme.md#visual-studio-enterprise-2022).
+[^4]: Precise version may be found in the [latest CI results](https://dev.azure.com/cppstat/GSL/_build?definitionId=1&branchFilter=26). Should be the version specified [here](https://github.com/actions/virtual-environments/blob/main/images/win/Windows2019-Readme.md#visual-studio-enterprise-2019).

 ---
 If you successfully port GSL to another platform, we would love to hear from you!
--- a/SECURITY.md
+++ b/SECURITY.md
@ -0,0 +1,41 @@
+<!-- BEGIN MICROSOFT SECURITY.MD V0.0.7 BLOCK -->
+
+## Security
+
+Microsoft takes the security of our software products and services seriously, which includes all source code repositories managed through our GitHub organizations, which include [Microsoft](https://github.com/Microsoft), [Azure](https://github.com/Azure), [DotNet](https://github.com/dotnet), [AspNet](https://github.com/aspnet), [Xamarin](https://github.com/xamarin), and [our GitHub organizations](https://opensource.microsoft.com/).
+
+If you believe you have found a security vulnerability in any Microsoft-owned repository that meets [Microsoft's definition of a security vulnerability](https://aka.ms/opensource/security/definition), please report it to us as described below.
+
+## Reporting Security Issues
+
+**Please do not report security vulnerabilities through public GitHub issues.**
+
+Instead, please report them to the Microsoft Security Response Center (MSRC) at [https://msrc.microsoft.com/create-report](https://aka.ms/opensource/security/create-report).
+
+If you prefer to submit without logging in, send email to [secure@microsoft.com](mailto:secure@microsoft.com).  If possible, encrypt your message with our PGP key; please download it from the [Microsoft Security Response Center PGP Key page](https://aka.ms/opensource/security/pgpkey).
+
+You should receive a response within 24 hours. If for some reason you do not, please follow up via email to ensure we received your original message. Additional information can be found at [microsoft.com/msrc](https://aka.ms/opensource/security/msrc). 
+
+Please include the requested information listed below (as much as you can provide) to help us better understand the nature and scope of the possible issue:
+
+  * Type of issue (e.g. buffer overflow, SQL injection, cross-site scripting, etc.)
+  * Full paths of source file(s) related to the manifestation of the issue
+  * The location of the affected source code (tag/branch/commit or direct URL)
+  * Any special configuration required to reproduce the issue
+  * Step-by-step instructions to reproduce the issue
+  * Proof-of-concept or exploit code (if possible)
+  * Impact of the issue, including how an attacker might exploit the issue
+
+This information will help us triage your report more quickly.
+
+If you are reporting for a bug bounty, more complete reports can contribute to a higher bounty award. Please visit our [Microsoft Bug Bounty Program](https://aka.ms/opensource/security/bounty) page for more details about our active programs.
+
+## Preferred Languages
+
+We prefer all communications to be in English.
+
+## Policy
+
+Microsoft follows the principle of [Coordinated Vulnerability Disclosure](https://aka.ms/opensource/security/cvd).
+
+<!-- END MICROSOFT SECURITY.MD BLOCK -->
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@ -4,65 +4,63 @@ trigger:
 pr:
  autoCancel: true

-# GCC
 stages:
 - stage: GCC
  dependsOn: []
-  variables:
-  - name: CC
-    value: gcc
-  - name: CXX
-    value: g++
  jobs:
  - template: ./pipelines/jobs.yml
    parameters:
-      jobName: 'Validate GCC latest'
-      imageName: ubuntu-20.04
-  - template: ./pipelines/jobs.yml
-    parameters:
-      jobName: 'Validate GCC Previous'
-      imageName: ubuntu-18.04
+      compiler: gcc
+      image: ubuntu-20.04
+      compilerVersions: [ 11, 10 ]
+      setupfile: 'setup_gcc.yml'

-# Clang
 - stage: Clang
  dependsOn: []
-  variables:
-  - name: CC
-    value: clang
-  - name: CXX
-    value: clang++
  jobs:
  - template: ./pipelines/jobs.yml
    parameters:
-      jobName: 'Validate Clang latest'
-      imageName: ubuntu-20.04
-  - template: ./pipelines/jobs.yml
-    parameters:
-      jobName: 'Validate Clang Previous'
-      imageName: ubuntu-18.04
+      compiler: clang
+      image: ubuntu-20.04
+      compilerVersions: [ 12, 11 ]
+      setupfile: 'setup_clang.yml'

-# MSVC
- stage: MSVC
+- stage: Xcode
  dependsOn: []
  jobs:
  - template: ./pipelines/jobs.yml
    parameters:
-      jobName: 'Validate MSVC latest'
-      imageName: windows-latest
-  - template: ./pipelines/jobs.yml
-    parameters:
-      jobName: 'Validate MSVC Previous'
-      imageName: vs2017-win2016
+      compiler: 'Xcode'
+      image: macOS-11
+      compilerVersions: [ '12.5.1', '13.2.1' ]
+      setupfile: 'setup_apple.yml'

-# Apple-Clang
- stage: Apple_Clang
+- stage: VS_MSVC
  dependsOn: []
  jobs:
  - template: ./pipelines/jobs.yml
    parameters:
-      jobName: 'Validate Apple-Clang latest'
-      imageName: macos-10.15
+      compiler: 'VS2019 (MSVC)'
+      compilerVersions: [ 'default' ]
+      image: windows-2019
  - template: ./pipelines/jobs.yml
    parameters:
-      jobName: 'Validate Apple-Clang Previous'
-      imageName: macos-10.14
+      compiler: 'VS2022 (MSVC)'
+      compilerVersions: [ 'default' ]
+      image: windows-2022
+
+- stage: VS_LLVM
+  dependsOn: []
+  jobs:
+  - template: ./pipelines/jobs.yml
+    parameters:
+      compiler: 'VS2019 (LLVM)'
+      compilerVersions: [ 'default' ]
+      image: windows-2019
+      extraCmakeArgs: '-T ClangCL'
+  - template: ./pipelines/jobs.yml
+    parameters:
+      compiler: 'VS2022 (LLVM)'
+      compilerVersions: [ 'default' ]
+      image: windows-2022
+      extraCmakeArgs: '-T ClangCL'
--- a/include/gsl/algorithm
+++ b/include/gsl/algorithm
@ -17,8 +17,8 @@
 #ifndef GSL_ALGORITHM_H
 #define GSL_ALGORITHM_H

-#include <gsl/assert> // for Expects
-#include <gsl/span>   // for dynamic_extent, span
+#include "assert" // for Expects
+#include "span"   // for dynamic_extent, span

 #include <algorithm>   // for copy_n
 #include <cstddef>     // for ptrdiff_t
--- a/include/gsl/assert
+++ b/include/gsl/assert
@ -22,6 +22,7 @@
 // Currently terminate is a no-op in this mode, so we add termination behavior back
 //
 #if defined(_MSC_VER) && (defined(_KERNEL_MODE) || (defined(_HAS_EXCEPTIONS) && !_HAS_EXCEPTIONS))
+#define GSL_KERNEL_MODE

 #define GSL_MSVC_USE_STL_NOEXCEPTION_WORKAROUND
 #include <intrin.h>
--- a/include/gsl/gsl
+++ b/include/gsl/gsl
@ -17,16 +17,16 @@
 #ifndef GSL_GSL_H
 #define GSL_GSL_H

-#include <gsl/algorithm>   // copy
-#include <gsl/assert>      // Ensures/Expects
-#include <gsl/byte>        // byte
-#include <gsl/pointers>    // owner, not_null
-#include <gsl/span>        // span
-#include <gsl/string_span> // zstring, string_span, zstring_builder...
-#include <gsl/util>        // finally()/narrow_cast()...
+#include "algorithm"   // copy
+#include "assert"      // Ensures/Expects
+#include "byte"        // byte
+#include "pointers"    // owner, not_null
+#include "span"        // span
+#include "string_span" // zstring, string_span, zstring_builder...
+#include "util"        // finally()/narrow_cast()...

 #ifdef __cpp_exceptions
-#include <gsl/narrow> // narrow()
+#include "narrow" // narrow()
 #endif

 #endif // GSL_GSL_H
--- a/include/gsl/gsl_algorithm
+++ b/include/gsl/gsl_algorithm
@ -1,3 +1,4 @@
 #pragma once
-#pragma message("This header will soon be removed. Use <gsl/algorithm> instead of <gsl/gsl_algorithm>")
-#include <gsl/algorithm>
+#pragma message(                                                                                   \
+    "This header will soon be removed. Use <gsl/algorithm> instead of <gsl/gsl_algorithm>")
+#include "algorithm"
--- a/include/gsl/gsl_assert
+++ b/include/gsl/gsl_assert
@ -1,3 +1,3 @@
 #pragma once
 #pragma message("This header will soon be removed. Use <gsl/assert> instead of <gsl/gsl_assert>")
-#include <gsl/assert>
+#include "assert"
--- a/include/gsl/gsl_byte
+++ b/include/gsl/gsl_byte
@ -1,3 +1,3 @@
 #pragma once
 #pragma message("This header will soon be removed. Use <gsl/byte> instead of <gsl/gsl_byte>")
-#include <gsl/byte>
+#include "byte"
--- a/include/gsl/gsl_narrow
+++ b/include/gsl/gsl_narrow
@ -1,3 +1,3 @@
 #pragma once
 #pragma message("This header will soon be removed. Use <gsl/narrow> instead of <gsl/gsl_narrow>")
-#include <gsl/narrow>
+#include "narrow"
--- a/include/gsl/gsl_util
+++ b/include/gsl/gsl_util
@ -1,3 +1,3 @@
 #pragma once
 #pragma message("This header will soon be removed. Use <gsl/util> instead of <gsl/gsl_util>")
-#include <gsl/util>
+#include "util"
--- a/include/gsl/narrow
+++ b/include/gsl/narrow
@ -16,8 +16,9 @@

 #ifndef GSL_NARROW_H
 #define GSL_NARROW_H
-#include <gsl/assert> // for Expects
-#include <gsl/util>   // for narrow_cast
+#include "assert"    // for GSL_SUPPRESS
+#include "util"      // for narrow_cast
+#include <exception> // for std::exception
 namespace gsl
 {
 struct narrowing_error : public std::exception
@ -26,19 +27,52 @@ struct narrowing_error : public std::exception
 };

 // narrow() : a checked version of narrow_cast() that throws if the cast changed the value
-template <class T, class U>
+template <class T, class U, typename std::enable_if<std::is_arithmetic<T>::value>::type* = nullptr>
 // clang-format off
 GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
 GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recognise noexcept(false)
-// clang-format on
+GSL_SUPPRESS(es.46) // NO-FORMAT: attribute // The warning suggests that a floating->unsigned conversion can occur
+                                            // in the static_cast below, and that gsl::narrow should be used instead.
+                                            // Suppress this warning, since gsl::narrow is defined in terms of
+                                            // static_cast
+    // clang-format on
    constexpr T narrow(U u) noexcept(false)
 {
    constexpr const bool is_different_signedness =
        (std::is_signed<T>::value != std::is_signed<U>::value);

+GSL_SUPPRESS(es.103) // NO-FORMAT: attribute // don't overflow
+GSL_SUPPRESS(es.104) // NO-FORMAT: attribute // don't underflow
+GSL_SUPPRESS(p.2) // NO-FORMAT: attribute // don't rely on undefined behavior
+    const T t = narrow_cast<T>(u); // While this is technically undefined behavior in some cases (i.e., if the source value is of floating-point type
+                                   // and cannot fit into the destination integral type), the resultant behavior is benign on the platforms
+                                   // that we target (i.e., no hardware trap representations are hit).
+
+#if defined(__clang__) || defined(__GNUC__)
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wfloat-equal"
+#endif
+    if (static_cast<U>(t) != u || (is_different_signedness && ((t < T{}) != (u < U{}))))
+    {
+        throw narrowing_error{};
+    }
+#if defined(__clang__) || defined(__GNUC__)
+    #pragma GCC diagnostic pop
+#endif
+
+    return t;
+}
+
+template <class T, class U, typename std::enable_if<!std::is_arithmetic<T>::value>::type* = nullptr>
+// clang-format off
+GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recognise noexcept(false)
+    // clang-format on
+    constexpr T narrow(U u) noexcept(false)
+{
    const T t = narrow_cast<T>(u);

-    if (static_cast<U>(t) != u || (is_different_signedness && ((t < T{}) != (u < U{}))))
+    if (static_cast<U>(t) != u)
    {
        throw narrowing_error{};
    }
--- a/include/gsl/pointers
+++ b/include/gsl/pointers
@ -17,7 +17,7 @@
 #ifndef GSL_POINTERS_H
 #define GSL_POINTERS_H

-#include <gsl/assert> // for Ensures, Expects
+#include "assert" // for Ensures, Expects

 #include <algorithm>    // for forward
 #include <cstddef>      // for ptrdiff_t, nullptr_t, size_t
@ -34,12 +34,19 @@ namespace gsl

 namespace details
 {
-template<typename T, typename = void>
-struct is_comparable_to_nullptr : std::false_type {};
+    template <typename T, typename = void>
+    struct is_comparable_to_nullptr : std::false_type
+    {
+    };

-template <typename T>
-struct is_comparable_to_nullptr<T, std::enable_if_t<std::is_convertible<decltype(std::declval<T>() != nullptr), bool>::value>> : std::true_type {};
-}   // namespace details
+    template <typename T>
+    struct is_comparable_to_nullptr<
+        T,
+        std::enable_if_t<std::is_convertible<decltype(std::declval<T>() != nullptr), bool>::value>>
+        : std::true_type
+    {
+    };
+} // namespace details

 //
 // GSL.owner: ownership pointers
--- a/include/gsl/span
+++ b/include/gsl/span
@ -17,15 +17,21 @@
 #ifndef GSL_SPAN_H
 #define GSL_SPAN_H

-#include <gsl/assert> // for Expects
-#include <gsl/byte>   // for byte
-#include <gsl/util>   // for narrow_cast
+#include "assert"   // for Expects
+#include "byte"     // for byte
+#include "span_ext" // for span specialization of gsl::at and other span-related extensions
+#include "util"     // for narrow_cast

 #include <array>       // for array
 #include <cstddef>     // for ptrdiff_t, size_t, nullptr_t
 #include <iterator>    // for reverse_iterator, distance, random_access_...
+#include <memory>      // for pointer_traits
 #include <type_traits> // for enable_if_t, declval, is_convertible, inte...

+#if defined(__has_include) && __has_include(<version>)
+#include <version>
+#endif
+
 #if defined(_MSC_VER) && !defined(__clang__)
 #pragma warning(push)

@ -60,12 +66,6 @@
 namespace gsl
 {

-// [views.constants], constants
-constexpr const std::size_t dynamic_extent = narrow_cast<std::size_t>(-1);
-
-template <class ElementType, std::size_t Extent = dynamic_extent>
-class span;
-
 // implementation details
 namespace details
 {
@ -115,6 +115,9 @@ namespace details
    class span_iterator
    {
    public:
+#if defined(__cpp_lib_ranges) || (defined(_MSVC_STL_VERSION) && defined(__cpp_lib_concepts))
+        using iterator_concept = std::contiguous_iterator_tag;
+#endif // __cpp_lib_ranges
        using iterator_category = std::random_access_iterator_tag;
        using value_type = std::remove_cv_t<Type>;
        using difference_type = std::ptrdiff_t;
@ -334,8 +337,26 @@ namespace details
        pointer begin_ = nullptr;
        pointer end_ = nullptr;
        pointer current_ = nullptr;
-    };

+        template <typename Ptr>
+        friend struct std::pointer_traits;
+    };
+}} // namespace gsl::details
+
+namespace std
+{
+template <class Type>
+struct pointer_traits<::gsl::details::span_iterator<Type>>
+{
+    using pointer = ::gsl::details::span_iterator<Type>;
+    using element_type = Type;
+    using difference_type = ptrdiff_t;
+
+    static constexpr element_type* to_address(const pointer i) noexcept { return i.current_; }
+};
+} // namespace std
+
+namespace gsl { namespace details {
    template <std::size_t Ext>
    class extent_type
    {
@ -687,14 +708,11 @@ private:
        template <class OtherExtentType>
        constexpr storage_type(KnownNotNull data, OtherExtentType ext)
            : ExtentType(ext), data_(data.p)
-        {
-            Expects(ExtentType::size() != dynamic_extent);
-        }
+        {}

        template <class OtherExtentType>
        constexpr storage_type(pointer data, OtherExtentType ext) : ExtentType(ext), data_(data)
        {
-            Expects(ExtentType::size() != dynamic_extent);
            Expects(data || ExtentType::size() == 0);
        }

--- a/include/gsl/span_ext
+++ b/include/gsl/span_ext
@ -27,16 +27,29 @@
 //
 ///////////////////////////////////////////////////////////////////////////////

-#include <gsl/span> // for span
-#include <gsl/util> // for narrow_cast, narrow
+#include "assert" // GSL_KERNEL_MODE
+#include "util"   // for narrow_cast, narrow

-#include <algorithm> // for lexicographical_compare
-#include <cstddef>   // for ptrdiff_t, size_t
+#include <cstddef> // for ptrdiff_t, size_t
 #include <utility>

+#ifndef GSL_KERNEL_MODE
+#include <algorithm> // for lexicographical_compare
+#endif               // GSL_KERNEL_MODE
+
 namespace gsl
 {

+// [span.views.constants], constants
+GSL_INLINE constexpr const std::size_t dynamic_extent = narrow_cast<std::size_t>(-1);
+
+template <class ElementType, std::size_t Extent = dynamic_extent>
+class span;
+
+// std::equal and std::lexicographical_compare are not /kernel compatible
+// so all comparison operators must be removed for kernel mode.
+#ifndef GSL_KERNEL_MODE
+
 // [span.comparison], span comparison operators
 template <class ElementType, std::size_t FirstExtent, std::size_t SecondExtent>
 constexpr bool operator==(span<ElementType, FirstExtent> l, span<ElementType, SecondExtent> r)
@ -74,6 +87,8 @@ constexpr bool operator>=(span<ElementType, Extent> l, span<ElementType, Extent>
    return !(l < r);
 }

+#endif // GSL_KERNEL_MODE
+
 //
 // make_span() - Utility functions for creating spans
 //
--- a/include/gsl/string_span
+++ b/include/gsl/string_span
@ -17,9 +17,9 @@
 #ifndef GSL_STRING_SPAN_H
 #define GSL_STRING_SPAN_H

-#include <gsl/assert>   // for Ensures, Expects
-#include <gsl/span_ext> // for operator!=, operator==, dynamic_extent
-#include <gsl/util>     // for narrow_cast
+#include "assert"   // for Ensures, Expects
+#include "span_ext" // for operator!=, operator==, dynamic_extent
+#include "util"     // for narrow_cast

 #include <algorithm> // for equal, lexicographical_compare
 #include <array>     // for array
@ -59,29 +59,21 @@ namespace gsl
 template <typename CharT, std::size_t Extent = dynamic_extent>
 using basic_zstring = CharT*;

-template <std::size_t Extent = dynamic_extent>
-using czstring = basic_zstring<const char, Extent>;
+using czstring = basic_zstring<const char, dynamic_extent>;

-template <std::size_t Extent = dynamic_extent>
-using cwzstring = basic_zstring<const wchar_t, Extent>;
+using cwzstring = basic_zstring<const wchar_t, dynamic_extent>;

-template <std::size_t Extent = dynamic_extent>
-using cu16zstring = basic_zstring<const char16_t, Extent>;
+using cu16zstring = basic_zstring<const char16_t, dynamic_extent>;

-template <std::size_t Extent = dynamic_extent>
-using cu32zstring = basic_zstring<const char32_t, Extent>;
+using cu32zstring = basic_zstring<const char32_t, dynamic_extent>;

-template <std::size_t Extent = dynamic_extent>
-using zstring = basic_zstring<char, Extent>;
+using zstring = basic_zstring<char, dynamic_extent>;

-template <std::size_t Extent = dynamic_extent>
-using wzstring = basic_zstring<wchar_t, Extent>;
+using wzstring = basic_zstring<wchar_t, dynamic_extent>;

-template <std::size_t Extent = dynamic_extent>
-using u16zstring = basic_zstring<char16_t, Extent>;
+using u16zstring = basic_zstring<char16_t, dynamic_extent>;

-template <std::size_t Extent = dynamic_extent>
-using u32zstring = basic_zstring<char32_t, Extent>;
+using u32zstring = basic_zstring<char32_t, dynamic_extent>;

 namespace details
 {
--- a/include/gsl/util
+++ b/include/gsl/util
@ -17,7 +17,7 @@
 #ifndef GSL_UTIL_H
 #define GSL_UTIL_H

-#include <gsl/assert> // for Expects
+#include "assert" // for Expects

 #include <array>
 #include <cstddef>          // for ptrdiff_t, size_t
@ -25,6 +25,13 @@
 #include <type_traits>      // for is_signed, integral_constant
 #include <utility>          // for exchange, forward

+#if defined(__has_include) && __has_include(<version>)
+#include <version>
+#if defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
+#include <span>
+#endif // __cpp_lib_span >= 202002L
+#endif //__has_include(<version>)
+
 #if defined(_MSC_VER) && !defined(__clang__)

 #pragma warning(push)
@ -38,6 +45,12 @@
 #define GSL_NODISCARD
 #endif // defined(__cplusplus) && (__cplusplus >= 201703L)

+#if defined(__cpp_inline_variables)
+#define GSL_INLINE inline
+#else
+#define GSL_INLINE
+#endif
+
 namespace gsl
 {
 //
@ -81,8 +94,8 @@ GSL_NODISCARD auto finally(F&& f) noexcept
 template <class T, class U>
 // clang-format off
 GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
-// clang-format on
-constexpr T narrow_cast(U&& u) noexcept
+    // clang-format on
+    constexpr T narrow_cast(U&& u) noexcept
 {
    return static_cast<T>(std::forward<U>(u));
 }
@ -94,7 +107,7 @@ template <class T, std::size_t N>
 // clang-format off
 GSL_SUPPRESS(bounds.4) // NO-FORMAT: attribute
 GSL_SUPPRESS(bounds.2) // NO-FORMAT: attribute
-// clang-format on
+    // clang-format on
    constexpr T& at(T (&arr)[N], const index i)
 {
    Expects(i >= 0 && i < narrow_cast<index>(N));
@ -105,7 +118,7 @@ template <class Cont>
 // clang-format off
 GSL_SUPPRESS(bounds.4) // NO-FORMAT: attribute
 GSL_SUPPRESS(bounds.2) // NO-FORMAT: attribute
-// clang-format on
+    // clang-format on
    constexpr auto at(Cont& cont, const index i) -> decltype(cont[cont.size()])
 {
    Expects(i >= 0 && i < narrow_cast<index>(cont.size()));
@ -116,13 +129,21 @@ GSL_SUPPRESS(bounds.2) // NO-FORMAT: attribute
 template <class T>
 // clang-format off
 GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
-// clang-format on
-constexpr T at(const std::initializer_list<T> cont, const index i)
+    // clang-format on
+    constexpr T at(const std::initializer_list<T> cont, const index i)
 {
    Expects(i >= 0 && i < narrow_cast<index>(cont.size()));
    return *(cont.begin() + i);
 }

+#if defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
+template <class T, size_t extent = std::dynamic_extent>
+constexpr auto at(std::span<T, extent> sp, const index i) -> decltype(sp[sp.size()])
+{
+    Expects(i >= 0 && i < narrow_cast<index>(sp.size()));
+    return sp[gsl::narrow_cast<size_t>(i)];
+}
+#endif // __cpp_lib_span >= 202002L
 } // namespace gsl

 #if defined(_MSC_VER) && !defined(__clang__)
--- a/pipelines/jobs.yml
+++ b/pipelines/jobs.yml
@ -1,26 +1,43 @@
 parameters:
-  jobName: ''
-  imageName: ''
+  CXXVersions: [ 14, 17, 20 ]
+  buildTypes: [ 'Debug', 'Release' ]
+  image: ''
+
+  compiler: ''
+  compilerVersions: ["default"] # if default value, simply uses whatever version is on the machine.
+                                # the text of this default value doesn't actually matter.
+  setupfile: ''
+  extraCmakeArgs: ''

 jobs:
- job:
-  displayName: ${{ parameters.imageName }}
-  pool:
-    vmImage: ${{ parameters.imageName }}
-  strategy:
-    matrix:
-      14_debug:
-        GSL_CXX_STANDARD: '14'
-        BUILD_TYPE: 'Debug'
-      14_release:
-        GSL_CXX_STANDARD: '14'
-        BUILD_TYPE: 'Release'
-      17_debug:
-        GSL_CXX_STANDARD: '17'
-        BUILD_TYPE: 'Debug'
-      17_release:
-        GSL_CXX_STANDARD: '17'
-        BUILD_TYPE: 'Release'
-  continueOnError: false
-  steps:
-  - template: ./steps.yml
+- ${{ each compilerVersion in parameters.compilerVersions }}:
+  - ${{ each CXXVersion in parameters.CXXVersions }}:
+    - ${{ each buildType in parameters.buildTypes }}:
+      - job:
+        displayName: ${{ format('{0} {1} C++{2} {3}', parameters.compiler, compilerVersion, CXXVersion, buildType) }}
+        pool:
+            vmImage: ${{ parameters.image }}
+        continueOnError: false
+
+        steps:
+          - ${{ if not(eq(parameters.setupfile, '')) }}:
+            - template: ${{ parameters.setupfile }}
+              parameters:
+                version: ${{ compilerVersion }}
+
+          - task: CMake@1
+            name: Configure
+            inputs:
+              workingDirectory: build
+              cmakeArgs: '-DGSL_CXX_STANDARD=${{ CXXVersion }} -DCMAKE_BUILD_TYPE=${{ buildType }} -DCI_TESTING:BOOL=ON -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON -Werror=dev ${{ parameters.extraCmakeArgs }} .. '
+
+          - task: CMake@1
+            name: Build
+            inputs:
+              workingDirectory: build
+              cmakeArgs: '--build . '
+
+          - script: ctest . --output-on-failure --no-compress-output
+            name: CTest
+            workingDirectory: build
+            failOnStderr: true
--- a/pipelines/setup_apple.yml
+++ b/pipelines/setup_apple.yml
@ -0,0 +1,9 @@
+parameters:
+    version: 0
+
+steps:
+  - script: |
+      if [ "${{ parameters.version }}" != "default" ]; then sudo xcode-select -switch /Applications/Xcode_${{ parameters.version }}.app; fi
+
+    displayName: "Setup Xcode Version"
+    failOnStderr: true
--- a/pipelines/setup_clang.yml
+++ b/pipelines/setup_clang.yml
@ -0,0 +1,13 @@
+parameters:
+    version: 0
+
+steps:
+  - script: |
+      echo "##vso[task.setvariable variable=CXX;]${CXX}"
+      echo "##vso[task.setvariable variable=CC;]${CC}"
+
+    displayName: "Setup Clang Version"
+    failOnStderr: true
+    env:
+      CC: clang-${{ parameters.version }}
+      CXX: clang++-${{ parameters.version }}
--- a/pipelines/setup_gcc.yml
+++ b/pipelines/setup_gcc.yml
@ -0,0 +1,14 @@
+parameters:
+    version: 0
+
+steps:
+  - script: |
+      echo "##vso[task.setvariable variable=CXX;]${CXX}"
+      echo "##vso[task.setvariable variable=CC;]${CC}"
+      if [ "${{ parameters.version }}" = "11" ]; then sudo apt-get install $CXX; fi
+
+    displayName: "Setup GCC Version"
+    failOnStderr: true
+    env:
+      CC: gcc-${{ parameters.version }}
+      CXX: g++-${{ parameters.version }}
--- a/pipelines/steps.yml
+++ b/pipelines/steps.yml
@ -1,17 +0,0 @@
-steps:
-  - task: CMake@1
-    name: Configure
-    inputs:
-      workingDirectory: build
-      cmakeArgs: '-DCMAKE_CXX_STANDARD=$(GSL_CXX_STANDARD) -DCMAKE_BUILD_TYPE=$(BUILD_TYPE) -Werror=dev .. '
-
-  - task: CMake@1
-    name: Build
-    inputs:
-      workingDirectory: build
-      cmakeArgs: '--build . '
-
-  - script: ctest . --output-on-failure --no-compress-output
-    name: CTest
-    workingDirectory: build
-    failOnStderr: true
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@ -9,8 +9,12 @@ include(ExternalProject)
 # will make visual studio generated project group files
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)

+if(CI_TESTING AND GSL_CXX_STANDARD EQUAL 20)
+    add_compile_definitions(FORCE_STD_SPAN_TESTS=1)
+endif()
+
 if(IOS)
-  add_compile_definitions(GTEST_HAS_DEATH_TEST=1)
+    add_compile_definitions(GTEST_HAS_DEATH_TEST=1 IOS_PROCESS_DELAY_WORKAROUND=1)
 endif()

 pkg_search_module(GTestMain gtest_main)
@ -54,10 +58,11 @@ if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
    find_package(Microsoft.GSL REQUIRED)
 endif()

-if (MSVC AND (GSL_CXX_STANDARD EQUAL 17))
+if (MSVC AND (GSL_CXX_STANDARD GREATER_EQUAL 17))
    set(GSL_CPLUSPLUS_OPT -Zc:__cplusplus -permissive-)
 endif()

+include(CheckCXXCompilerFlag)
 # this interface adds compile options to how the tests are run
 # please try to keep entries ordered =)
 add_library(gsl_tests_config INTERFACE)
@ -84,6 +89,7 @@ if(MSVC) # MSVC or simulating MSVC
        >
        $<$<CXX_COMPILER_ID:Clang>:
          -Weverything
+          -Wfloat-equal
          -Wno-c++98-compat
          -Wno-c++98-compat-pedantic
          -Wno-covered-switch-default # GTest
@ -101,6 +107,10 @@ if(MSVC) # MSVC or simulating MSVC
          >
        >
    )
+    check_cxx_compiler_flag("-Wno-reserved-identifier" WARN_RESERVED_ID)
+    if (WARN_RESERVED_ID)
+        target_compile_options(gsl_tests_config INTERFACE "-Wno-reserved-identifier")
+    endif()
 else()
    target_compile_options(gsl_tests_config INTERFACE
        -fno-strict-aliasing
@ -113,6 +123,7 @@ else()
        -Wpedantic
        -Wshadow
        -Wsign-conversion
+        -Wfloat-equal
        -Wno-deprecated-declarations # Allow tests for [[deprecated]] elements
        $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>>:
          -Weverything
@ -135,6 +146,11 @@ else()
          $<$<AND:$<VERSION_GREATER:$<CXX_COMPILER_VERSION>,4.99>,$<VERSION_LESS:$<CXX_COMPILER_VERSION>,6>>:
            $<$<EQUAL:${GSL_CXX_STANDARD},17>:-Wno-undefined-func-template>
          >
+          $<$<AND:$<EQUAL:${GSL_CXX_STANDARD},20>,$<OR:$<CXX_COMPILER_VERSION:11.0.0>,$<CXX_COMPILER_VERSION:10.0.0>>>:
+              -Wno-zero-as-null-pointer-constant  # failing Clang Ubuntu 20.04 tests, seems to be a bug with clang 10.0.0
+                                                  # and clang 11.0.0. (operator< is being re-written by the compiler
+                                                  # as operator<=> and raising the warning)
+          >
        >
        $<$<CXX_COMPILER_ID:AppleClang>:
          $<$<AND:$<VERSION_GREATER:$<CXX_COMPILER_VERSION>,9.1>,$<VERSION_LESS:$<CXX_COMPILER_VERSION>,10>>:
@ -164,36 +180,27 @@ target_include_directories(gsl_tests_config SYSTEM INTERFACE
    googletest/googletest/include
 )

-set_property(TARGET  PROPERTY FOLDER "GSL_tests")
-
-function(add_gsl_test name)
-    add_executable(${name} ${name}.cpp)
-    target_link_libraries(${name}
-        Microsoft.GSL::GSL
-        gsl_tests_config
-        ${GTestMain_LIBRARIES}
-    )
-    add_test(
-        ${name}
-        ${name}
-    )
-    # group all tests under GSL_tests
-    set_property(TARGET ${name} PROPERTY FOLDER "GSL_tests")
-endfunction()
-
-add_gsl_test(span_tests)
-add_gsl_test(span_ext_tests)
-add_gsl_test(span_compatibility_tests)
-add_gsl_test(string_span_tests)
-add_gsl_test(at_tests)
-add_gsl_test(notnull_tests)
-add_gsl_test(assertion_tests)
-add_gsl_test(utils_tests)
-add_gsl_test(owner_tests)
-add_gsl_test(byte_tests)
-add_gsl_test(algorithm_tests)
-add_gsl_test(strict_notnull_tests)
+add_executable(gsl_tests
+    algorithm_tests.cpp
+    assertion_tests.cpp
+    at_tests.cpp
+    byte_tests.cpp
+    notnull_tests.cpp
+    owner_tests.cpp
+    span_compatibility_tests.cpp
+    span_ext_tests.cpp
+    span_tests.cpp
+    strict_notnull_tests.cpp
+    string_span_tests.cpp
+    utils_tests.cpp
+)

+target_link_libraries(gsl_tests
+    Microsoft.GSL::GSL
+    gsl_tests_config
+    ${GTestMain_LIBRARIES}
+)
+add_test(gsl_tests gsl_tests)

 # No exception tests

@ -222,12 +229,17 @@ if(MSVC) # MSVC or simulating MSVC
        >
        $<$<CXX_COMPILER_ID:Clang>:
          -Weverything
+          -Wfloat-equal
          -Wno-c++98-compat
          -Wno-c++98-compat-pedantic
          -Wno-missing-prototypes
          -Wno-unknown-attributes
        >
    )
+    check_cxx_compiler_flag("-Wno-reserved-identifier" WARN_RESERVED_ID)
+    if (WARN_RESERVED_ID)
+        target_compile_options(gsl_tests_config_noexcept INTERFACE "-Wno-reserved-identifier")
+    endif()
 else()
    target_compile_options(gsl_tests_config_noexcept INTERFACE
        -fno-exceptions
@ -241,6 +253,7 @@ else()
        -Wpedantic
        -Wshadow
        -Wsign-conversion
+        -Wfloat-equal
        $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>>:
          -Weverything
          -Wno-c++98-compat
@ -268,19 +281,9 @@ else()
    )
 endif(MSVC)

-function(add_gsl_test_noexcept name)
-    add_executable(${name} ${name}.cpp)
-    target_link_libraries(${name}
-        Microsoft.GSL::GSL
-        gsl_tests_config_noexcept
-        ${GTestMain_LIBRARIES}
-    )
-    add_test(
-      ${name}
-      ${name}
-    )
-    # group all tests under GSL_tests_noexcept
-    set_property(TARGET ${name} PROPERTY FOLDER "GSL_tests_noexcept")
-endfunction()
-
-add_gsl_test_noexcept(no_exception_ensure_tests)
+add_executable(gsl_noexcept_tests no_exception_ensure_tests.cpp)
+target_link_libraries(gsl_noexcept_tests
+    Microsoft.GSL::GSL
+    gsl_tests_config_noexcept
+)
+add_test(gsl_noexcept_tests gsl_noexcept_tests)
--- a/tests/CMakeLists.txt.in
+++ b/tests/CMakeLists.txt.in
@ -4,7 +4,7 @@ project(googletest-download NONE)
 include(ExternalProject)
 ExternalProject_Add(googletest
  GIT_REPOSITORY    https://github.com/google/googletest.git
-  GIT_TAG           389cb68b87193358358ae87cc56d257fd0d80189
+  GIT_TAG           1b18723e874b256c1e39378c6774a90701d70f7a
  SOURCE_DIR        "${CMAKE_CURRENT_BINARY_DIR}/googletest-src"
  BINARY_DIR        "${CMAKE_CURRENT_BINARY_DIR}/googletest-build"
  CONFIGURE_COMMAND ""
--- a/tests/algorithm_tests.cpp
+++ b/tests/algorithm_tests.cpp
@ -14,23 +14,19 @@
 //
 ///////////////////////////////////////////////////////////////////////////////

-#include <gtest/gtest.h>
+#include <array>         // for array
+#include <cstddef>       // for size_t
 #include <gsl/algorithm> // for copy
-#include <gsl/span>          // for span
-#include <array>   // for array
-#include <cstddef> // for size_t
+#include <gsl/span>      // for span
+#include <gtest/gtest.h>

-namespace
-{
-    static constexpr char deathstring[] = "Expected Death";
-}
+#include "deathTestCommon.h"

 namespace gsl
 {
 struct fail_fast;
 } // namespace gsl

-using namespace std;
 using namespace gsl;

 TEST(algorithm_tests, same_type)
@ -76,8 +72,8 @@ TEST(algorithm_tests, same_type)
        std::array<int, 5> src{1, 2, 3, 4, 5};
        std::array<int, 10> dst{};

-        const span<int> src_span(src);
-        const span<int, 10> dst_span(dst);
+        const gsl::span<int> src_span(src);
+        const gsl::span<int, 10> dst_span(dst);

        copy(src_span, dst_span);
        copy(src_span, dst_span.subspan(src_span.size()));
@ -204,10 +200,11 @@ TEST(algorithm_tests, incompatible_type)

 TEST(algorithm_tests, small_destination_span)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. small_destination_span";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    std::array<int, 12> src{1, 2, 3, 4};
    std::array<int, 4> dst{};
@ -217,9 +214,9 @@ TEST(algorithm_tests, small_destination_span)
    const span<int> dst_span_dyn(dst);
    const span<int, 4> dst_span_static(dst);

-    EXPECT_DEATH(copy(src_span_dyn, dst_span_dyn), deathstring);
-    EXPECT_DEATH(copy(src_span_dyn, dst_span_static), deathstring);
-    EXPECT_DEATH(copy(src_span_static, dst_span_dyn), deathstring);
+    EXPECT_DEATH(copy(src_span_dyn, dst_span_dyn), expected);
+    EXPECT_DEATH(copy(src_span_dyn, dst_span_static), expected);
+    EXPECT_DEATH(copy(src_span_static, dst_span_dyn), expected);

 #ifdef CONFIRM_COMPILATION_ERRORS
    copy(src_span_static, dst_span_static);
--- a/tests/assertion_tests.cpp
+++ b/tests/assertion_tests.cpp
@ -14,14 +14,14 @@
 //
 ///////////////////////////////////////////////////////////////////////////////

-#include <gtest/gtest.h>
+#include "deathTestCommon.h"
 #include <gsl/assert> // for fail_fast (ptr only), Ensures, Expects
+#include <gtest/gtest.h>

 using namespace gsl;

 namespace
 {
-static constexpr char deathstring[] = "Expected Death";

 int f(int i)
 {
@ -39,23 +39,22 @@ int g(int i)

 TEST(assertion_tests, expects)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. expects";
        std::abort();
    });

    EXPECT_TRUE(f(2) == 2);
-    EXPECT_DEATH(f(10), deathstring);
+    EXPECT_DEATH(f(10), GetExpectedDeathString(terminateHandler));
 }

-
 TEST(assertion_tests, ensures)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. ensures";
        std::abort();
    });

    EXPECT_TRUE(g(2) == 3);
-    EXPECT_DEATH(g(9), deathstring);
+    EXPECT_DEATH(g(9), GetExpectedDeathString(terminateHandler));
 }
--- a/tests/at_tests.cpp
+++ b/tests/at_tests.cpp
@ -22,31 +22,33 @@
 #include <cstddef>          // for size_t
 #include <initializer_list> // for initializer_list
 #include <vector>           // for vector
+#if defined(__cplusplus) && __cplusplus >= 202002L
+#include <span>
+#endif // __cplusplus >= 202002L

-namespace
-{
-    static constexpr char deathstring[] = "Expected Death";
-}
+#include "deathTestCommon.h"

 TEST(at_tests, static_array)
 {
    int a[4] = {1, 2, 3, 4};
    const int(&c_a)[4] = a;

-    for (int i = 0; i < 4; ++i) {
+    for (int i = 0; i < 4; ++i)
+    {
        EXPECT_TRUE(&gsl::at(a, i) == &a[i]);
        EXPECT_TRUE(&gsl::at(c_a, i) == &a[i]);
    }

-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. static_array";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

-    EXPECT_DEATH(gsl::at(a, -1), deathstring);
-    EXPECT_DEATH(gsl::at(a, 4), deathstring);
-    EXPECT_DEATH(gsl::at(c_a, -1), deathstring);
-    EXPECT_DEATH(gsl::at(c_a, 4), deathstring);
+    EXPECT_DEATH(gsl::at(a, -1), expected);
+    EXPECT_DEATH(gsl::at(a, 4), expected);
+    EXPECT_DEATH(gsl::at(c_a, -1), expected);
+    EXPECT_DEATH(gsl::at(c_a, 4), expected);
 }

 TEST(at_tests, std_array)
@ -54,20 +56,22 @@ TEST(at_tests, std_array)
    std::array<int, 4> a = {1, 2, 3, 4};
    const std::array<int, 4>& c_a = a;

-    for (int i = 0; i < 4; ++i) {
+    for (int i = 0; i < 4; ++i)
+    {
        EXPECT_TRUE(&gsl::at(a, i) == &a[static_cast<std::size_t>(i)]);
        EXPECT_TRUE(&gsl::at(c_a, i) == &a[static_cast<std::size_t>(i)]);
    }

-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. std_array";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

-    EXPECT_DEATH(gsl::at(a, -1), deathstring);
-    EXPECT_DEATH(gsl::at(a, 4), deathstring);
-    EXPECT_DEATH(gsl::at(c_a, -1), deathstring);
-    EXPECT_DEATH(gsl::at(c_a, 4), deathstring);
+    EXPECT_DEATH(gsl::at(a, -1), expected);
+    EXPECT_DEATH(gsl::at(a, 4), expected);
+    EXPECT_DEATH(gsl::at(c_a, -1), expected);
+    EXPECT_DEATH(gsl::at(c_a, 4), expected);
 }

 TEST(at_tests, std_vector)
@ -75,42 +79,74 @@ TEST(at_tests, std_vector)
    std::vector<int> a = {1, 2, 3, 4};
    const std::vector<int>& c_a = a;

-    for (int i = 0; i < 4; ++i) {
+    for (int i = 0; i < 4; ++i)
+    {
        EXPECT_TRUE(&gsl::at(a, i) == &a[static_cast<std::size_t>(i)]);
        EXPECT_TRUE(&gsl::at(c_a, i) == &a[static_cast<std::size_t>(i)]);
    }

-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. std_vector";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

-    EXPECT_DEATH(gsl::at(a, -1), deathstring);
-    EXPECT_DEATH(gsl::at(a, 4), deathstring);
-    EXPECT_DEATH(gsl::at(c_a, -1), deathstring);
-    EXPECT_DEATH(gsl::at(c_a, 4), deathstring);
+    EXPECT_DEATH(gsl::at(a, -1), expected);
+    EXPECT_DEATH(gsl::at(a, 4), expected);
+    EXPECT_DEATH(gsl::at(c_a, -1), expected);
+    EXPECT_DEATH(gsl::at(c_a, 4), expected);
 }

 TEST(at_tests, InitializerList)
 {
    const std::initializer_list<int> a = {1, 2, 3, 4};

-    for (int i = 0; i < 4; ++i) {
+    for (int i = 0; i < 4; ++i)
+    {
        EXPECT_TRUE(gsl::at(a, i) == i + 1);
        EXPECT_TRUE(gsl::at({1, 2, 3, 4}, i) == i + 1);
    }

-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. InitializerList";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

-    EXPECT_DEATH(gsl::at(a, -1), deathstring);
-    EXPECT_DEATH(gsl::at(a, 4), deathstring);
-    EXPECT_DEATH(gsl::at({1, 2, 3, 4}, -1), deathstring);
-    EXPECT_DEATH(gsl::at({1, 2, 3, 4}, 4), deathstring);
+    EXPECT_DEATH(gsl::at(a, -1), expected);
+    EXPECT_DEATH(gsl::at(a, 4), expected);
+    EXPECT_DEATH(gsl::at({1, 2, 3, 4}, -1), expected);
+    EXPECT_DEATH(gsl::at({1, 2, 3, 4}, 4), expected);
 }

+#if defined(FORCE_STD_SPAN_TESTS) || defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
+TEST(at_tests, std_span)
+{
+    std::vector<int> vec{1, 2, 3, 4, 5};
+    std::span sp{vec};
+
+    std::vector<int> cvec{1, 2, 3, 4, 5};
+    std::span csp{cvec};
+
+    for (gsl::index i = 0; i < gsl::narrow_cast<gsl::index>(vec.size()); ++i)
+    {
+        EXPECT_TRUE(&gsl::at(sp, i) == &vec[gsl::narrow_cast<size_t>(i)]);
+        EXPECT_TRUE(&gsl::at(csp, i) == &cvec[gsl::narrow_cast<size_t>(i)]);
+    }
+
+    const auto terminateHandler = std::set_terminate([] {
+        std::cerr << "Expected Death. std_span";
+        std::abort();
+    });
+    const auto expected = GetExpectedDeathString(terminateHandler);
+
+    EXPECT_DEATH(gsl::at(sp, -1), expected);
+    EXPECT_DEATH(gsl::at(sp, gsl::narrow_cast<gsl::index>(sp.size())), expected);
+    EXPECT_DEATH(gsl::at(csp, -1), expected);
+    EXPECT_DEATH(gsl::at(csp, gsl::narrow_cast<gsl::index>(sp.size())), expected);
+}
+#endif // defined(FORCE_STD_SPAN_TESTS) || defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
+
 #if !defined(_MSC_VER) || defined(__clang__) || _MSC_VER >= 1910
 static constexpr bool test_constexpr()
 {
@ -119,7 +155,8 @@ static constexpr bool test_constexpr()
    std::array<int, 4> a2 = {1, 2, 3, 4};
    const std::array<int, 4>& c_a2 = a2;

-    for (int i = 0; i < 4; ++i) {
+    for (int i = 0; i < 4; ++i)
+    {
        if (&gsl::at(a1, i) != &a1[i]) return false;
        if (&gsl::at(c_a1, i) != &a1[i]) return false;
        // requires C++17:
--- a/tests/byte_tests.cpp
+++ b/tests/byte_tests.cpp
@ -37,7 +37,9 @@ TEST(byte_tests, construction)
        EXPECT_TRUE(static_cast<unsigned char>(b) == 4);
    }

+    // clang-format off
    GSL_SUPPRESS(es.49)
+    // clang-format on
    {
        const byte b = byte(12);
        EXPECT_TRUE(static_cast<unsigned char>(b) == 12);
@ -55,7 +57,7 @@ TEST(byte_tests, construction)

 #if defined(__cplusplus) && (__cplusplus >= 201703L)
    {
-        const byte b { 14 };
+        const byte b{14};
        EXPECT_TRUE(static_cast<unsigned char>(b) == 14);
    }
 #endif
@ -122,7 +124,7 @@ TEST(byte_tests, aliasing)
    EXPECT_TRUE(res == i);
 }

-}
+} // namespace

 #ifdef CONFIRM_COMPILATION_ERRORS
 copy(src_span_static, dst_span_static);
--- a/tests/deathTestCommon.h
+++ b/tests/deathTestCommon.h
@ -0,0 +1,11 @@
+#pragma once
+#include <gsl/assert>
+
+constexpr char deathstring[] = "Expected Death";
+constexpr char failed_set_terminate_deathstring[] = ".*";
+
+// This prevents a failed call to set_terminate from failing the test suite.
+constexpr const char* GetExpectedDeathString(std::terminate_handler handle)
+{
+    return handle ? deathstring : failed_set_terminate_deathstring;
+}
--- a/tests/no_exception_ensure_tests.cpp
+++ b/tests/no_exception_ensure_tests.cpp
@ -14,8 +14,11 @@
 //
 ///////////////////////////////////////////////////////////////////////////////

+#include <chrono>
 #include <cstdlib>  // for std::exit
 #include <gsl/span> // for span
+#include <iostream>
+#include <thread>

 int operator_subscript_no_throw() noexcept
 {
@ -42,6 +45,10 @@ void setup_termination_handler() noexcept

 int main() noexcept
 {
+    std::cout << "Running main() from " __FILE__ "\n";
+#if defined(IOS_PROCESS_DELAY_WORKAROUND)
+    std::this_thread::sleep_for(std::chrono::seconds(1));
+#endif
    setup_termination_handler();
    operator_subscript_no_throw();
    return -1;
--- a/tests/notnull_tests.cpp
+++ b/tests/notnull_tests.cpp
@ -25,13 +25,9 @@
 #include <string>    // for basic_string, operator==, string, operator<<
 #include <typeinfo>  // for type_info

+#include "deathTestCommon.h"
 using namespace gsl;

-namespace
-{
-static constexpr char deathstring[] = "Expected Death";
-} //namespace
-
 struct MyBase
 {
 };
@ -64,7 +60,9 @@ struct CustomPtr
 template <typename T, typename U>
 std::string operator==(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 {
+    // clang-format off
    GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+    // clang-format on
    return reinterpret_cast<const void*>(lhs.p_) == reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                          : "false";
 }
@ -72,7 +70,9 @@ std::string operator==(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 template <typename T, typename U>
 std::string operator!=(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 {
+    // clang-format off
    GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+    // clang-format on
    return reinterpret_cast<const void*>(lhs.p_) != reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                          : "false";
 }
@ -80,7 +80,9 @@ std::string operator!=(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 template <typename T, typename U>
 std::string operator<(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 {
+    // clang-format off
    GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+    // clang-format on
    return reinterpret_cast<const void*>(lhs.p_) < reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                         : "false";
 }
@ -88,7 +90,9 @@ std::string operator<(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 template <typename T, typename U>
 std::string operator>(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 {
+    // clang-format off
    GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+    // clang-format on
    return reinterpret_cast<const void*>(lhs.p_) > reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                         : "false";
 }
@ -96,7 +100,9 @@ std::string operator>(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 template <typename T, typename U>
 std::string operator<=(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 {
+    // clang-format off
    GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+    // clang-format on
    return reinterpret_cast<const void*>(lhs.p_) <= reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                          : "false";
 }
@ -104,7 +110,9 @@ std::string operator<=(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 template <typename T, typename U>
 std::string operator>=(CustomPtr<T> const& lhs, CustomPtr<U> const& rhs)
 {
+    // clang-format off
    GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+    // clang-format on
    return reinterpret_cast<const void*>(lhs.p_) >= reinterpret_cast<const void*>(rhs.p_) ? "true"
                                                                                          : "false";
 }
@ -118,12 +126,19 @@ struct NonCopyableNonMovable
    NonCopyableNonMovable& operator=(NonCopyableNonMovable&&) = delete;
 };

-GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+namespace
+{
+// clang-format off
+GSL_SUPPRESS(f .4) // NO-FORMAT: attribute
+// clang-format on
 bool helper(not_null<int*> p) { return *p == 12; }
-GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+// clang-format off
+GSL_SUPPRESS(f .4) // NO-FORMAT: attribute
+// clang-format on
 bool helper_const(not_null<const int*> p) { return *p == 12; }

 int* return_pointer() { return nullptr; }
+} // namespace

 TEST(notnull_tests, TestNotNullConstructors)
 {
@ -142,10 +157,12 @@ TEST(notnull_tests, TestNotNullConstructors)
 #endif
    }

-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. TestNotNullConstructors";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);
+
    {
        // from shared pointer
        int i = 12;
@ -157,7 +174,7 @@ TEST(notnull_tests, TestNotNullConstructors)
            std::make_shared<int>(10)); // shared_ptr<int> is nullptr assignable

        int* pi = nullptr;
-        EXPECT_DEATH((not_null<decltype(pi)>(pi)), deathstring);
+        EXPECT_DEATH((not_null<decltype(pi)>(pi)), expected);
    }

    {
@ -214,8 +231,8 @@ TEST(notnull_tests, TestNotNullConstructors)
    {
        // from returned pointer

-        EXPECT_DEATH(helper(return_pointer()), deathstring);
-        EXPECT_DEATH(helper_const(return_pointer()), deathstring);
+        EXPECT_DEATH(helper(return_pointer()), expected);
+        EXPECT_DEATH(helper_const(return_pointer()), expected);
    }
 }

@ -275,17 +292,18 @@ TEST(notnull_tests, TestNotNullCasting)

 TEST(notnull_tests, TestNotNullAssignment)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. TestNotNullAssignmentd";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    int i = 12;
    not_null<int*> p(&i);
    EXPECT_TRUE(helper(p));

    int* q = nullptr;
-    EXPECT_DEATH(p = not_null<int*>(q), deathstring);
+    EXPECT_DEATH(p = not_null<int*>(q), expected);
 }

 TEST(notnull_tests, TestNotNullRawPointerComparison)
@ -434,17 +452,18 @@ TEST(notnull_tests, TestNotNullConstructorTypeDeduction)
        EXPECT_TRUE(*x == 42);
    }

-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. TestNotNullConstructorTypeDeduction";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    {
        auto workaround_macro = []() {
            int* p1 = nullptr;
            const not_null x{p1};
        };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    {
@ -452,14 +471,14 @@ TEST(notnull_tests, TestNotNullConstructorTypeDeduction)
            const int* p1 = nullptr;
            const not_null x{p1};
        };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    {
        int* p = nullptr;

-        EXPECT_DEATH(helper(not_null{p}), deathstring);
-        EXPECT_DEATH(helper_const(not_null{p}), deathstring);
+        EXPECT_DEATH(helper(not_null{p}), expected);
+        EXPECT_DEATH(helper_const(not_null{p}), expected);
    }

 #ifdef CONFIRM_COMPILATION_ERRORS
@ -495,10 +514,11 @@ TEST(notnull_tests, TestMakeNotNull)
        EXPECT_TRUE(*x == 42);
    }

-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. TestMakeNotNull";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    {
        const auto workaround_macro = []() {
@ -506,7 +526,7 @@ TEST(notnull_tests, TestMakeNotNull)
            const auto x = make_not_null(p1);
            EXPECT_TRUE(*x == 42);
        };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    {
@ -515,21 +535,21 @@ TEST(notnull_tests, TestMakeNotNull)
            const auto x = make_not_null(p1);
            EXPECT_TRUE(*x == 42);
        };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    {
        int* p = nullptr;

-        EXPECT_DEATH(helper(make_not_null(p)), deathstring);
-        EXPECT_DEATH(helper_const(make_not_null(p)), deathstring);
+        EXPECT_DEATH(helper(make_not_null(p)), expected);
+        EXPECT_DEATH(helper_const(make_not_null(p)), expected);
    }

 #ifdef CONFIRM_COMPILATION_ERRORS
    {
-        EXPECT_DEATH(make_not_null(nullptr), deathstring);
-        EXPECT_DEATH(helper(make_not_null(nullptr)), deathstring);
-        EXPECT_DEATH(helper_const(make_not_null(nullptr)), deathstring);
+        EXPECT_DEATH(make_not_null(nullptr), expected);
+        EXPECT_DEATH(helper(make_not_null(nullptr)), expected);
+        EXPECT_DEATH(helper_const(make_not_null(nullptr)), expected);
    }
 #endif
 }
--- a/tests/owner_tests.cpp
+++ b/tests/owner_tests.cpp
@ -20,7 +20,7 @@

 using namespace gsl;

-GSL_SUPPRESS(f.23) // NO-FORMAT: attribute
+GSL_SUPPRESS(f .23) // NO-FORMAT: attribute
 void f(int* i) { *i += 1; }

 TEST(owner_tests, basic_test)
@ -34,10 +34,10 @@ TEST(owner_tests, basic_test)

 TEST(owner_tests, check_pointer_constraint)
 {
-    #ifdef CONFIRM_COMPILATION_ERRORS
+#ifdef CONFIRM_COMPILATION_ERRORS
    {
        owner<int> integerTest = 10;
        owner<std::shared_ptr<int>> sharedPtrTest(new int(10));
    }
-    #endif
+#endif
 }
--- a/tests/span_compatibility_tests.cpp
+++ b/tests/span_compatibility_tests.cpp
@ -17,7 +17,7 @@
 #include <gtest/gtest.h>

 #include <gsl/byte> // for byte
-#include <gsl/span>     // for span, span_iterator, operator==, operator!=
+#include <gsl/span> // for span, span_iterator, operator==, operator!=

 #include <array>       // for array
 #include <cstddef>     // for ptrdiff_t
@ -55,14 +55,14 @@ void ArrayConvertibilityCheck()
        EXPECT_TRUE(sp_const_nullptr_1.data() == stl_nullptr.data());
        EXPECT_TRUE(sp_const_nullptr_1.size() == 3);

-        span<const T* const> sp_const_nullptr_2{std::as_const(stl_nullptr)};
+        gsl::span<const T* const> sp_const_nullptr_2{std::as_const(stl_nullptr)};
        EXPECT_TRUE(sp_const_nullptr_2.data() == stl_nullptr.data());
        EXPECT_TRUE(sp_const_nullptr_2.size() == 3);

-        static_assert(std::is_same<decltype(span{stl_nullptr}), span<T*, 3>>::value,
+        static_assert(std::is_same<decltype(gsl::span{stl_nullptr}), gsl::span<T*, 3>>::value,
                      "std::is_same< decltype(span{stl_nullptr}), span<T*, 3>>::value");
        static_assert(
-            std::is_same<decltype(span{std::as_const(stl_nullptr)}), span<T* const, 3>>::value,
+            std::is_same<decltype(gsl::span{std::as_const(stl_nullptr)}), gsl::span<T* const, 3>>::value,
            "std::is_same< decltype(span{std::as_const(stl_nullptr)}), span<T* const, "
            "3>>::value");
    }
--- a/tests/span_ext_tests.cpp
+++ b/tests/span_ext_tests.cpp
@ -16,27 +16,26 @@

 #include <gtest/gtest.h>

+#include <gsl/span> // for span and span_ext
 #include <gsl/util> // for narrow_cast, at
-#include <gsl/span_ext> // for operator==, operator!=, make_span

-#include <array>       // for array
-#include <iostream>    // for cerr
-#include <vector>      // for vector
+#include <array>    // for array
+#include <iostream> // for cerr
+#include <vector>   // for vector

 using namespace std;
 using namespace gsl;

-namespace
-{
-static constexpr char deathstring[] = "Expected Death";
-} // namespace
+#include "deathTestCommon.h"

 TEST(span_ext_test, make_span_from_pointer_length_constructor)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. from_pointer_length_constructor";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);
+
    int arr[4] = {1, 2, 3, 4};

    {
@ -49,7 +48,7 @@ TEST(span_ext_test, make_span_from_pointer_length_constructor)

    {
        int* p = nullptr;
-        auto s = make_span(p, narrow_cast<span<int>::size_type>(0));
+        auto s = make_span(p, narrow_cast<gsl::span<int>::size_type>(0));
        EXPECT_TRUE(s.size() == 0);
        EXPECT_TRUE(s.data() == nullptr);
    }
@ -57,7 +56,7 @@ TEST(span_ext_test, make_span_from_pointer_length_constructor)
    {
        int* p = nullptr;
        auto workaround_macro = [=]() { make_span(p, 2); };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }
 }

@ -88,273 +87,275 @@ TEST(span_ext_test, make_span_from_pointer_pointer_construction)
 }

 TEST(span_ext_test, make_span_from_array_constructor)
- {
-     int arr[5] = {1, 2, 3, 4, 5};
-     int arr2d[2][3] = {1, 2, 3, 4, 5, 6};
-     int arr3d[2][3][2] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};
+{
+    int arr[5] = {1, 2, 3, 4, 5};
+    int arr2d[2][3] = {1, 2, 3, 4, 5, 6};
+    int arr3d[2][3][2] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};

-     {
-         const auto s = make_span(arr);
-         EXPECT_TRUE(s.size() == 5);
-         EXPECT_TRUE(s.data() == std::addressof(arr[0]));
-     }
+    {
+        const auto s = make_span(arr);
+        EXPECT_TRUE(s.size() == 5);
+        EXPECT_TRUE(s.data() == std::addressof(arr[0]));
+    }

-     {
-         const auto s = make_span(std::addressof(arr2d[0]), 1);
-         EXPECT_TRUE(s.size() == 1);
-         EXPECT_TRUE(s.data() == std::addressof(arr2d[0]));
-     }
+    {
+        const auto s = make_span(std::addressof(arr2d[0]), 1);
+        EXPECT_TRUE(s.size() == 1);
+        EXPECT_TRUE(s.data() == std::addressof(arr2d[0]));
+    }

-     {
-         const auto s = make_span(std::addressof(arr3d[0]), 1);
-         EXPECT_TRUE(s.size() == 1);
-         EXPECT_TRUE(s.data() == std::addressof(arr3d[0]));
-     }
- }
+    {
+        const auto s = make_span(std::addressof(arr3d[0]), 1);
+        EXPECT_TRUE(s.size() == 1);
+        EXPECT_TRUE(s.data() == std::addressof(arr3d[0]));
+    }
+}

- TEST(span_ext_test, make_span_from_dynamic_array_constructor)
- {
-     double(*arr)[3][4] = new double[100][3][4];
+TEST(span_ext_test, make_span_from_dynamic_array_constructor)
+{
+    double(*arr)[3][4] = new double[100][3][4];

-     {
-         auto s = make_span(&arr[0][0][0], 10);
-         EXPECT_TRUE(s.size() == 10);
-         EXPECT_TRUE(s.data() == &arr[0][0][0]);
-     }
+    {
+        auto s = make_span(&arr[0][0][0], 10);
+        EXPECT_TRUE(s.size() == 10);
+        EXPECT_TRUE(s.data() == &arr[0][0][0]);
+    }

-     delete[] arr;
- }
+    delete[] arr;
+}

- TEST(span_ext_test, make_span_from_std_array_constructor)
- {
-     std::array<int, 4> arr = {1, 2, 3, 4};
+TEST(span_ext_test, make_span_from_std_array_constructor)
+{
+    std::array<int, 4> arr = {1, 2, 3, 4};

-     {
-         auto s = make_span(arr);
-         EXPECT_TRUE(s.size() == arr.size());
-         EXPECT_TRUE(s.data() == arr.data());
-     }
+    {
+        auto s = make_span(arr);
+        EXPECT_TRUE(s.size() == arr.size());
+        EXPECT_TRUE(s.data() == arr.data());
+    }

-     // This test checks for the bug found in gcc 6.1, 6.2, 6.3, 6.4, 6.5 7.1, 7.2, 7.3 - issue #590
-     {
-         span<int> s1 = make_span(arr);
+    // This test checks for the bug found in gcc 6.1, 6.2, 6.3, 6.4, 6.5 7.1, 7.2, 7.3 - issue #590
+    {
+        gsl::span<int> s1 = make_span(arr);

-         static span<int> s2;
-         s2 = s1;
+        static gsl::span<int> s2;
+        s2 = s1;

- #if defined(__GNUC__) && __GNUC__ == 6 && (__GNUC_MINOR__ == 4 || __GNUC_MINOR__ == 5) &&          \
-     __GNUC_PATCHLEVEL__ == 0 && defined(__OPTIMIZE__)
-         // Known to be broken in gcc 6.4 and 6.5 with optimizations
-         // Issue in gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83116
-         EXPECT_TRUE(s1.size() == 4);
-         EXPECT_TRUE(s2.size() == 0);
- #else
-         EXPECT_TRUE(s1.size() == s2.size());
- #endif
-     }
- }
+#if defined(__GNUC__) && __GNUC__ == 6 && (__GNUC_MINOR__ == 4 || __GNUC_MINOR__ == 5) &&          \
+    __GNUC_PATCHLEVEL__ == 0 && defined(__OPTIMIZE__)
+        // Known to be broken in gcc 6.4 and 6.5 with optimizations
+        // Issue in gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83116
+        EXPECT_TRUE(s1.size() == 4);
+        EXPECT_TRUE(s2.size() == 0);
+#else
+        EXPECT_TRUE(s1.size() == s2.size());
+#endif
+    }
+}

- TEST(span_ext_test, make_span_from_const_std_array_constructor)
- {
-     const std::array<int, 4> arr = {1, 2, 3, 4};
+TEST(span_ext_test, make_span_from_const_std_array_constructor)
+{
+    const std::array<int, 4> arr = {1, 2, 3, 4};

-     {
-         auto s = make_span(arr);
-         EXPECT_TRUE(s.size() == arr.size());
-         EXPECT_TRUE(s.data() == arr.data());
-     }
- }
+    {
+        auto s = make_span(arr);
+        EXPECT_TRUE(s.size() == arr.size());
+        EXPECT_TRUE(s.data() == arr.data());
+    }
+}

- TEST(span_ext_test, make_span_from_std_array_const_constructor)
- {
-     std::array<const int, 4> arr = {1, 2, 3, 4};
+TEST(span_ext_test, make_span_from_std_array_const_constructor)
+{
+    std::array<const int, 4> arr = {1, 2, 3, 4};

-     {
-         auto s = make_span(arr);
-         EXPECT_TRUE(s.size() == arr.size());
-         EXPECT_TRUE(s.data() == arr.data());
-     }
- }
+    {
+        auto s = make_span(arr);
+        EXPECT_TRUE(s.size() == arr.size());
+        EXPECT_TRUE(s.data() == arr.data());
+    }
+}

- TEST(span_ext_test, make_span_from_container_constructor)
- {
-     std::vector<int> v = {1, 2, 3};
-     const std::vector<int> cv = v;
+TEST(span_ext_test, make_span_from_container_constructor)
+{
+    std::vector<int> v = {1, 2, 3};
+    const std::vector<int> cv = v;

-     {
-         auto s = make_span(v);
-         EXPECT_TRUE(s.size() == v.size());
-         EXPECT_TRUE(s.data() == v.data());
+    {
+        auto s = make_span(v);
+        EXPECT_TRUE(s.size() == v.size());
+        EXPECT_TRUE(s.data() == v.data());

-         auto cs = make_span(cv);
-         EXPECT_TRUE(cs.size() == cv.size());
-         EXPECT_TRUE(cs.data() == cv.data());
-     }
- }
+        auto cs = make_span(cv);
+        EXPECT_TRUE(cs.size() == cv.size());
+        EXPECT_TRUE(cs.data() == cv.data());
+    }
+}

- TEST(span_test, interop_with_gsl_at)
- {
-     int arr[5] = {1, 2, 3, 4, 5};
-     span<int> s{arr};
-     EXPECT_TRUE(at(s, 0) ==  1);
-     EXPECT_TRUE(at(s, 1) == 2);
- }
+TEST(span_test, interop_with_gsl_at)
+{
+    int arr[5] = {1, 2, 3, 4, 5};
+    gsl::span<int> s{arr};
+    EXPECT_TRUE(at(s, 0) == 1);
+    EXPECT_TRUE(at(s, 1) == 2);
+}

- TEST(span_ext_test, iterator_free_functions)
- {
-     int a[] = {1, 2, 3, 4};
-     span<int> s{a};
+TEST(span_ext_test, iterator_free_functions)
+{
+    int a[] = {1, 2, 3, 4};
+    gsl::span<int> s{a};

-     EXPECT_TRUE((std::is_same<decltype(s.begin()), decltype(begin(s))>::value));
-     EXPECT_TRUE((std::is_same<decltype(s.end()), decltype(end(s))>::value));
+    EXPECT_TRUE((std::is_same<decltype(s.begin()), decltype(begin(s))>::value));
+    EXPECT_TRUE((std::is_same<decltype(s.end()), decltype(end(s))>::value));

-     EXPECT_TRUE((std::is_same<decltype(std::cbegin(s)), decltype(cbegin(s))>::value));
-     EXPECT_TRUE((std::is_same<decltype(std::cend(s)), decltype(cend(s))>::value));
+    EXPECT_TRUE((std::is_same<decltype(std::cbegin(s)), decltype(cbegin(s))>::value));
+    EXPECT_TRUE((std::is_same<decltype(std::cend(s)), decltype(cend(s))>::value));

-     EXPECT_TRUE((std::is_same<decltype(s.rbegin()), decltype(rbegin(s))>::value));
-     EXPECT_TRUE((std::is_same<decltype(s.rend()), decltype(rend(s))>::value));
+    EXPECT_TRUE((std::is_same<decltype(s.rbegin()), decltype(rbegin(s))>::value));
+    EXPECT_TRUE((std::is_same<decltype(s.rend()), decltype(rend(s))>::value));

-     EXPECT_TRUE((std::is_same<decltype(std::crbegin(s)), decltype(crbegin(s))>::value));
-     EXPECT_TRUE((std::is_same<decltype(std::crend(s)), decltype(crend(s))>::value));
+    EXPECT_TRUE((std::is_same<decltype(std::crbegin(s)), decltype(crbegin(s))>::value));
+    EXPECT_TRUE((std::is_same<decltype(std::crend(s)), decltype(crend(s))>::value));

-     EXPECT_TRUE(s.begin() == begin(s));
-     EXPECT_TRUE(s.end() == end(s));
+    EXPECT_TRUE(s.begin() == begin(s));
+    EXPECT_TRUE(s.end() == end(s));

-     EXPECT_TRUE(s.rbegin() == rbegin(s));
-     EXPECT_TRUE(s.rend() == rend(s));
+    EXPECT_TRUE(s.rbegin() == rbegin(s));
+    EXPECT_TRUE(s.rend() == rend(s));

-     EXPECT_TRUE(s.begin() == cbegin(s));
-     EXPECT_TRUE(s.end() == cend(s));
+    EXPECT_TRUE(s.begin() == cbegin(s));
+    EXPECT_TRUE(s.end() == cend(s));

-     EXPECT_TRUE(s.rbegin() == crbegin(s));
-     EXPECT_TRUE(s.rend() == crend(s));
- }
+    EXPECT_TRUE(s.rbegin() == crbegin(s));
+    EXPECT_TRUE(s.rend() == crend(s));
+}

- TEST(span_ext_test, ssize_free_function)
- {
-     int a[] = {1, 2, 3, 4};
-     span<int> s{a};
+TEST(span_ext_test, ssize_free_function)
+{
+    int a[] = {1, 2, 3, 4};
+    gsl::span<int> s{a};

-     EXPECT_FALSE((std::is_same<decltype(s.size()), decltype(ssize(s))>::value));
-     EXPECT_TRUE(s.size() == static_cast<std::size_t>(ssize(s)));
- }
+    EXPECT_FALSE((std::is_same<decltype(s.size()), decltype(ssize(s))>::value));
+    EXPECT_TRUE(s.size() == static_cast<std::size_t>(ssize(s)));
+}

-  TEST(span_ext_test, comparison_operators)
- {
-     {
-         span<int> s1;
-         span<int> s2;
-         EXPECT_TRUE(s1 == s2);
-         EXPECT_FALSE(s1 != s2);
-         EXPECT_FALSE(s1 < s2);
-         EXPECT_TRUE(s1 <= s2);
-         EXPECT_FALSE(s1 > s2);
-         EXPECT_TRUE(s1 >= s2);
-         EXPECT_TRUE(s2 == s1);
-         EXPECT_FALSE(s2 != s1);
-         EXPECT_FALSE(s2 != s1);
-         EXPECT_TRUE(s2 <= s1);
-         EXPECT_FALSE(s2 > s1);
-         EXPECT_TRUE(s2 >= s1);
-     }
+#ifndef GSL_KERNEL_MODE
+TEST(span_ext_test, comparison_operators)
+{
+    {
+        gsl::span<int> s1;
+        gsl::span<int> s2;
+        EXPECT_TRUE(s1 == s2);
+        EXPECT_FALSE(s1 != s2);
+        EXPECT_FALSE(s1 < s2);
+        EXPECT_TRUE(s1 <= s2);
+        EXPECT_FALSE(s1 > s2);
+        EXPECT_TRUE(s1 >= s2);
+        EXPECT_TRUE(s2 == s1);
+        EXPECT_FALSE(s2 != s1);
+        EXPECT_FALSE(s2 != s1);
+        EXPECT_TRUE(s2 <= s1);
+        EXPECT_FALSE(s2 > s1);
+        EXPECT_TRUE(s2 >= s1);
+    }

-     {
-         int arr[] = {2, 1};
-         span<int> s1 = arr;
-         span<int> s2 = arr;
+    {
+        int arr[] = {2, 1};
+        gsl::span<int> s1 = arr;
+        gsl::span<int> s2 = arr;

-         EXPECT_TRUE(s1 == s2);
-         EXPECT_FALSE(s1 != s2);
-         EXPECT_FALSE(s1 < s2);
-         EXPECT_TRUE(s1 <= s2);
-         EXPECT_FALSE(s1 > s2);
-         EXPECT_TRUE(s1 >= s2);
-         EXPECT_TRUE(s2 == s1);
-         EXPECT_FALSE(s2 != s1);
-         EXPECT_FALSE(s2 < s1);
-         EXPECT_TRUE(s2 <= s1);
-         EXPECT_FALSE(s2 > s1);
-         EXPECT_TRUE(s2 >= s1);
-     }
+        EXPECT_TRUE(s1 == s2);
+        EXPECT_FALSE(s1 != s2);
+        EXPECT_FALSE(s1 < s2);
+        EXPECT_TRUE(s1 <= s2);
+        EXPECT_FALSE(s1 > s2);
+        EXPECT_TRUE(s1 >= s2);
+        EXPECT_TRUE(s2 == s1);
+        EXPECT_FALSE(s2 != s1);
+        EXPECT_FALSE(s2 < s1);
+        EXPECT_TRUE(s2 <= s1);
+        EXPECT_FALSE(s2 > s1);
+        EXPECT_TRUE(s2 >= s1);
+    }

-     {
-         int arr[] = {2, 1}; // bigger
+    {
+        int arr[] = {2, 1}; // bigger

-         span<int> s1;
-         span<int> s2 = arr;
+        gsl::span<int> s1;
+        gsl::span<int> s2 = arr;

-         EXPECT_TRUE(s1 != s2);
-         EXPECT_TRUE(s2 != s1);
-         EXPECT_FALSE(s1 == s2);
-         EXPECT_FALSE(s2 == s1);
-         EXPECT_TRUE(s1 < s2);
-         EXPECT_FALSE(s2 < s1);
-         EXPECT_TRUE(s1 <= s2);
-         EXPECT_FALSE(s2 <= s1);
-         EXPECT_TRUE(s2 > s1);
-         EXPECT_FALSE(s1 > s2);
-         EXPECT_TRUE(s2 >= s1);
-         EXPECT_FALSE(s1 >= s2);
-     }
+        EXPECT_TRUE(s1 != s2);
+        EXPECT_TRUE(s2 != s1);
+        EXPECT_FALSE(s1 == s2);
+        EXPECT_FALSE(s2 == s1);
+        EXPECT_TRUE(s1 < s2);
+        EXPECT_FALSE(s2 < s1);
+        EXPECT_TRUE(s1 <= s2);
+        EXPECT_FALSE(s2 <= s1);
+        EXPECT_TRUE(s2 > s1);
+        EXPECT_FALSE(s1 > s2);
+        EXPECT_TRUE(s2 >= s1);
+        EXPECT_FALSE(s1 >= s2);
+    }

-     {
-         int arr1[] = {1, 2};
-         int arr2[] = {1, 2};
-         span<int> s1 = arr1;
-         span<int> s2 = arr2;
+    {
+        int arr1[] = {1, 2};
+        int arr2[] = {1, 2};
+        gsl::span<int> s1 = arr1;
+        gsl::span<int> s2 = arr2;

-         EXPECT_TRUE(s1 == s2);
-         EXPECT_FALSE(s1 != s2);
-         EXPECT_FALSE(s1 < s2);
-         EXPECT_TRUE(s1 <= s2);
-         EXPECT_FALSE(s1 > s2);
-         EXPECT_TRUE(s1 >= s2);
-         EXPECT_TRUE(s2 == s1);
-         EXPECT_FALSE(s2 != s1);
-         EXPECT_FALSE(s2 < s1);
-         EXPECT_TRUE(s2 <= s1);
-         EXPECT_FALSE(s2 > s1);
-         EXPECT_TRUE(s2 >= s1);
-     }
+        EXPECT_TRUE(s1 == s2);
+        EXPECT_FALSE(s1 != s2);
+        EXPECT_FALSE(s1 < s2);
+        EXPECT_TRUE(s1 <= s2);
+        EXPECT_FALSE(s1 > s2);
+        EXPECT_TRUE(s1 >= s2);
+        EXPECT_TRUE(s2 == s1);
+        EXPECT_FALSE(s2 != s1);
+        EXPECT_FALSE(s2 < s1);
+        EXPECT_TRUE(s2 <= s1);
+        EXPECT_FALSE(s2 > s1);
+        EXPECT_TRUE(s2 >= s1);
+    }

-     {
-         int arr[] = {1, 2, 3};
+    {
+        int arr[] = {1, 2, 3};

-         span<int> s1 = {&arr[0], 2}; // shorter
-         span<int> s2 = arr;          // longer
+        gsl::span<int> s1 = {&arr[0], 2}; // shorter
+        gsl::span<int> s2 = arr;          // longer

-         EXPECT_TRUE(s1 != s2);
-         EXPECT_TRUE(s2 != s1);
-         EXPECT_FALSE(s1 == s2);
-         EXPECT_FALSE(s2 == s1);
-         EXPECT_TRUE(s1 < s2);
-         EXPECT_FALSE(s2 < s1);
-         EXPECT_TRUE(s1 <= s2);
-         EXPECT_FALSE(s2 <= s1);
-         EXPECT_TRUE(s2 > s1);
-         EXPECT_FALSE(s1 > s2);
-         EXPECT_TRUE(s2 >= s1);
-         EXPECT_FALSE(s1 >= s2);
-     }
+        EXPECT_TRUE(s1 != s2);
+        EXPECT_TRUE(s2 != s1);
+        EXPECT_FALSE(s1 == s2);
+        EXPECT_FALSE(s2 == s1);
+        EXPECT_TRUE(s1 < s2);
+        EXPECT_FALSE(s2 < s1);
+        EXPECT_TRUE(s1 <= s2);
+        EXPECT_FALSE(s2 <= s1);
+        EXPECT_TRUE(s2 > s1);
+        EXPECT_FALSE(s1 > s2);
+        EXPECT_TRUE(s2 >= s1);
+        EXPECT_FALSE(s1 >= s2);
+    }

-     {
-         int arr1[] = {1, 2}; // smaller
-         int arr2[] = {2, 1}; // bigger
+    {
+        int arr1[] = {1, 2}; // smaller
+        int arr2[] = {2, 1}; // bigger

-         span<int> s1 = arr1;
-         span<int> s2 = arr2;
+        gsl::span<int> s1 = arr1;
+        gsl::span<int> s2 = arr2;

-         EXPECT_TRUE(s1 != s2);
-         EXPECT_TRUE(s2 != s1);
-         EXPECT_FALSE(s1 == s2);
-         EXPECT_FALSE(s2 == s1);
-         EXPECT_TRUE(s1 < s2);
-         EXPECT_FALSE(s2 < s1);
-         EXPECT_TRUE(s1 <= s2);
-         EXPECT_FALSE(s2 <= s1);
-         EXPECT_TRUE(s2 > s1);
-         EXPECT_FALSE(s1 > s2);
-         EXPECT_TRUE(s2 >= s1);
-         EXPECT_FALSE(s1 >= s2);
-     }
- }
+        EXPECT_TRUE(s1 != s2);
+        EXPECT_TRUE(s2 != s1);
+        EXPECT_FALSE(s1 == s2);
+        EXPECT_FALSE(s2 == s1);
+        EXPECT_TRUE(s1 < s2);
+        EXPECT_FALSE(s2 < s1);
+        EXPECT_TRUE(s1 <= s2);
+        EXPECT_FALSE(s2 <= s1);
+        EXPECT_TRUE(s2 > s1);
+        EXPECT_FALSE(s1 > s2);
+        EXPECT_TRUE(s2 >= s1);
+        EXPECT_FALSE(s1 >= s2);
+    }
+}
+#endif // GSL_KERNEL_MODE
--- a/tests/span_tests.cpp
+++ b/tests/span_tests.cpp
--- a/tests/strict_notnull_tests.cpp
+++ b/tests/strict_notnull_tests.cpp
@ -14,30 +14,40 @@
 //
 ///////////////////////////////////////////////////////////////////////////////

+#include <gsl/pointers> // for not_null, operator<, operator<=, operator>
 #include <gtest/gtest.h>
-#include <gsl/pointers>           // for not_null, operator<, operator<=, operator>

-namespace gsl
-{
-struct fail_fast;
-} // namespace gsl
+#include "deathTestCommon.h"

 using namespace gsl;

-GSL_SUPPRESS(f.4)  // NO-FORMAT: attribute
+namespace
+{
+// clang-format off
+GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+// clang-format on
 bool helper(not_null<int*> p) { return *p == 12; }

+// clang-format off
 GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+// clang-format on
 bool helper_const(not_null<const int*> p) { return *p == 12; }

+// clang-format off
 GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+// clang-format on
 bool strict_helper(strict_not_null<int*> p) { return *p == 12; }

+// clang-format off
 GSL_SUPPRESS(f.4) // NO-FORMAT: attribute
+// clang-format on
 bool strict_helper_const(strict_not_null<const int*> p) { return *p == 12; }

+#ifdef CONFIRM_COMPILATION_ERRORS
 int* return_pointer() { return nullptr; }
 const int* return_pointer_const() { return nullptr; }
+#endif
+} // namespace

 TEST(strict_notnull_tests, TestStrictNotNull)
 {
@ -123,17 +133,14 @@ TEST(strict_notnull_tests, TestStrictNotNull)
 }

 #if defined(__cplusplus) && (__cplusplus >= 201703L)
-namespace
-{
-static constexpr char deathstring[] = "Expected Death";
-}

 TEST(strict_notnull_tests, TestStrictNotNullConstructorTypeDeduction)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. TestStrictNotNullConstructorTypeDeduction";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    {
        int i = 42;
@ -161,7 +168,7 @@ TEST(strict_notnull_tests, TestStrictNotNullConstructorTypeDeduction)
            int* p1 = nullptr;
            const strict_not_null x{p1};
        };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    {
@ -169,14 +176,14 @@ TEST(strict_notnull_tests, TestStrictNotNullConstructorTypeDeduction)
            const int* p1 = nullptr;
            const strict_not_null x{p1};
        };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    {
        int* p = nullptr;

-        EXPECT_DEATH(helper(strict_not_null{p}), deathstring);
-        EXPECT_DEATH(helper_const(strict_not_null{p}), deathstring);
+        EXPECT_DEATH(helper(strict_not_null{p}), expected);
+        EXPECT_DEATH(helper_const(strict_not_null{p}), expected);
    }

 #ifdef CONFIRM_COMPILATION_ERRORS
--- a/tests/string_span_tests.cpp
+++ b/tests/string_span_tests.cpp
@ -16,7 +16,7 @@

 #include <gtest/gtest.h>

-#include <gsl/assert>  // for Expects, fail_fast (ptr only)
+#include <gsl/assert>      // for Expects, fail_fast (ptr only)
 #include <gsl/pointers>    // for owner
 #include <gsl/span>        // for span, dynamic_extent
 #include <gsl/string_span> // for basic_string_span, operator==, ensure_z
@ -28,13 +28,10 @@
 #include <type_traits> // for remove_reference<>::type
 #include <vector>      // for vector, allocator

-using namespace std;
+#include "deathTestCommon.h"
+
 using namespace gsl;

-namespace
-{
-static constexpr char deathstring[] = "Expected Death";
-}
 // Generic string functions

 namespace generic
@ -76,8 +73,7 @@ T create()

 template <class T>
 void use(basic_string_span<T, gsl::dynamic_extent>)
-{
-}
+{}
 #endif

 czstring_span<> CreateTempName(string_span<> span)
@ -85,7 +81,8 @@ czstring_span<> CreateTempName(string_span<> span)
    Expects(span.size() > 1);

    std::size_t last = 0;
-    if (span.size() > 4) {
+    if (span.size() > 4)
+    {
        span[0] = 't';
        span[1] = 'm';
        span[2] = 'p';
@ -102,7 +99,8 @@ cwzstring_span<> CreateTempNameW(wstring_span<> span)
    Expects(span.size() > 1);

    std::size_t last = 0;
-    if (span.size() > 4) {
+    if (span.size() > 4)
+    {
        span[0] = L't';
        span[1] = L'm';
        span[2] = L'p';
@ -119,7 +117,8 @@ cu16zstring_span<> CreateTempNameU16(u16string_span<> span)
    Expects(span.size() > 1);

    std::size_t last = 0;
-    if (span.size() > 4) {
+    if (span.size() > 4)
+    {
        span[0] = u't';
        span[1] = u'm';
        span[2] = u'p';
@ -136,7 +135,8 @@ cu32zstring_span<> CreateTempNameU32(u32string_span<> span)
    Expects(span.size() > 1);

    std::size_t last = 0;
-    if (span.size() > 4) {
+    if (span.size() > 4)
+    {
        span[0] = U't';
        span[1] = U'm';
        span[2] = U'p';
@ -950,10 +950,11 @@ TEST(string_span_tests, Conversion)

 TEST(string_span_tests, zstring)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. zstring";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    // create zspan from zero terminated string
    {
@ -973,7 +974,7 @@ TEST(string_span_tests, zstring)
        buf[0] = 'a';

        auto workaround_macro = [&]() { const zstring_span<> zspan({buf, 1}); };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    // usage scenario: create zero-terminated temp file name and pass to a legacy API
@ -981,8 +982,9 @@ TEST(string_span_tests, zstring)
        char buf[10];

        auto name = CreateTempName({buf, 10});
-        if (!name.empty()) {
-            czstring<> str = name.assume_z();
+        if (!name.empty())
+        {
+            czstring str = name.assume_z();
            EXPECT_TRUE(generic::strlen(str) == 3);
            EXPECT_TRUE(*(str + 3) == '\0');
        }
@ -991,10 +993,11 @@ TEST(string_span_tests, zstring)

 TEST(string_span_tests, wzstring)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. wzstring";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    // create zspan from zero terminated string
    {
@ -1014,7 +1017,7 @@ TEST(string_span_tests, wzstring)
        buf[0] = L'a';

        const auto workaround_macro = [&]() { const wzstring_span<> zspan({buf, 1}); };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    // usage scenario: create zero-terminated temp file name and pass to a legacy API
@ -1022,8 +1025,9 @@ TEST(string_span_tests, wzstring)
        wchar_t buf[10];

        const auto name = CreateTempNameW({buf, 10});
-        if (!name.empty()) {
-            cwzstring<> str = name.assume_z();
+        if (!name.empty())
+        {
+            cwzstring str = name.assume_z();
            EXPECT_TRUE(generic::strnlen(str, 10) == 3);
            EXPECT_TRUE(*(str + 3) == L'\0');
        }
@ -1032,10 +1036,11 @@ TEST(string_span_tests, wzstring)

 TEST(string_span_tests, u16zstring)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. u16zstring";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    // create zspan from zero terminated string
    {
@ -1055,7 +1060,7 @@ TEST(string_span_tests, u16zstring)
        buf[0] = u'a';

        const auto workaround_macro = [&]() { const u16zstring_span<> zspan({buf, 1}); };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    // usage scenario: create zero-terminated temp file name and pass to a legacy API
@ -1063,8 +1068,9 @@ TEST(string_span_tests, u16zstring)
        char16_t buf[10];

        const auto name = CreateTempNameU16({buf, 10});
-        if (!name.empty()) {
-            cu16zstring<> str = name.assume_z();
+        if (!name.empty())
+        {
+            cu16zstring str = name.assume_z();
            EXPECT_TRUE(generic::strnlen(str, 10) == 3);
            EXPECT_TRUE(*(str + 3) == L'\0');
        }
@ -1073,10 +1079,11 @@ TEST(string_span_tests, u16zstring)

 TEST(string_span_tests, u32zstring)
 {
-    std::set_terminate([] {
+    const auto terminateHandler = std::set_terminate([] {
        std::cerr << "Expected Death. u31zstring";
        std::abort();
    });
+    const auto expected = GetExpectedDeathString(terminateHandler);

    // create zspan from zero terminated string
    {
@ -1096,7 +1103,7 @@ TEST(string_span_tests, u32zstring)
        buf[0] = u'a';

        const auto workaround_macro = [&]() { const u32zstring_span<> zspan({buf, 1}); };
-        EXPECT_DEATH(workaround_macro(), deathstring);
+        EXPECT_DEATH(workaround_macro(), expected);
    }

    // usage scenario: create zero-terminated temp file name and pass to a legacy API
@ -1104,8 +1111,9 @@ TEST(string_span_tests, u32zstring)
        char32_t buf[10];

        const auto name = CreateTempNameU32({buf, 10});
-        if (!name.empty()) {
-            cu32zstring<> str = name.assume_z();
+        if (!name.empty())
+        {
+            cu32zstring str = name.assume_z();
            EXPECT_TRUE(generic::strnlen(str, 10) == 3);
            EXPECT_TRUE(*(str + 3) == L'\0');
        }
--- a/tests/utils_tests.cpp
+++ b/tests/utils_tests.cpp
@ -16,14 +16,15 @@

 #include <gtest/gtest.h>

-#include <gsl/util>     // finally, narrow_cast
-#include <gsl/narrow>   // for narrow, narrowing_error
 #include <algorithm>   // for move
+#include <complex>
+#include <cstddef>     // for std::ptrdiff_t
 #include <functional>  // for reference_wrapper, _Bind_helper<>::type
+#include <gsl/narrow>  // for narrow, narrowing_error
+#include <gsl/util>    // finally, narrow_cast
 #include <limits>      // for numeric_limits
 #include <stdint.h>    // for uint32_t, int32_t
 #include <type_traits> // for is_same
-#include <cstddef>     // for std::ptrdiff_t

 using namespace gsl;

@ -32,8 +33,7 @@ namespace
 void f(int& i) { i += 1; }
 static int j = 0;
 void g() { j += 1; }
-}
-
+} // namespace

 TEST(utils_tests, sanity_check_for_gsl_index_typedef)
 {
@ -123,6 +123,7 @@ TEST(utils_tests, narrow_cast)
    EXPECT_TRUE(uc == 44);
 }

+#ifndef GSL_KERNEL_MODE
 TEST(utils_tests, narrow)
 {
    int n = 120;
@ -144,4 +145,11 @@ TEST(utils_tests, narrow)

    n = -42;
    EXPECT_THROW(narrow<unsigned>(n), narrowing_error);
+
+    EXPECT_TRUE(
+        narrow<std::complex<float>>(std::complex<double>(4, 2)) == std::complex<float>(4, 2));
+    EXPECT_THROW(narrow<std::complex<float>>(std::complex<double>(4.2)), narrowing_error);
+
+    EXPECT_TRUE(narrow<int>(float(1)) == 1);
 }
+#endif // GSL_KERNEL_MODE