Added library.json

added GSL_ prefix to VS_ADD_NATIVE_VISUALIZERS

.github/workflows/android.yml

@@ -0,0 +1,50 @@
+name: CI_Android
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  Android:
+    runs-on: macos-latest
+    defaults:
+      run:
+        working-directory: build
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Create build directory
+        run: mkdir -p build
+        working-directory: .
+
+      - name: Start emulator
+        run: |
+          echo "y" | $ANDROID_HOME/tools/bin/sdkmanager --install 'system-images;android-24;default;x86_64'
+          echo "no" | $ANDROID_HOME/tools/bin/avdmanager create avd -n xamarin_android_emulator -k 'system-images;android-24;default;x86_64' --force
+          $ANDROID_HOME/emulator/emulator -list-avds
+          echo "Starting emulator"
+          # Start emulator in background
+          nohup $ANDROID_HOME/emulator/emulator -avd xamarin_android_emulator -no-snapshot > /dev/null 2>&1 &
+          echo "Emulator starting"
+
+      - name: Configure
+        run: cmake -DCMAKE_TOOLCHAIN_FILE=$ANDROID_HOME/ndk-bundle/build/cmake/android.toolchain.cmake -DANDROID_PLATFORM=16 -DANDROID_ABI=x86_64 -DCMAKE_BUILD_TYPE=Debug ..
+
+      - name: Build
+        run: cmake --build . --parallel
+
+      - name: Wait for emulator ready
+        run: |
+          $ANDROID_HOME/platform-tools/adb wait-for-device shell 'while [[ -z $(getprop sys.boot_completed | tr -d '\r') ]]; do sleep 10; done; input keyevent 82'
+          $ANDROID_HOME/platform-tools/adb devices
+          $ANDROID_HOME/platform-tools/adb shell getprop ro.product.cpu.abi
+          echo "Emulator started"
+
+      - name: Deploy tests
+        run: |
+          adb push tests /data/local/tmp
+          adb shell find /data/local/tmp/tests -maxdepth 1 -exec chmod +x {} \\\;
+
+      - name: Test
+        run: adb shell find /data/local/tmp/tests -name "*_tests" -maxdepth 1 -exec {} \\\;

.github/workflows/ios.yml

@@ -0,0 +1,51 @@
+name: CI_iOS
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  iOS:
+    runs-on: macos-latest
+    defaults:
+      run:
+        working-directory: build
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Create build directory
+        run: mkdir -p build
+        working-directory: .
+
+      - name: Configure
+        run: |
+          cmake \
+            -GXcode \
+            -DCMAKE_SYSTEM_NAME=iOS \
+            "-DCMAKE_OSX_ARCHITECTURES=arm64;x86_64" \
+            -DCMAKE_OSX_DEPLOYMENT_TARGET=8 \
+            -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 \
+            ..
+
+      - name: Build
+        run: cmake --build . --parallel `sysctl -n hw.ncpu` --config Release -- -sdk iphonesimulator
+
+      - name: Start simulator
+        run: |
+          RUNTIME=`xcrun simctl list runtimes iOS -j|jq '.runtimes|last.identifier'`
+          UDID=`xcrun simctl list devices iPhone available -j|jq -r ".devices[$RUNTIME]|last.udid"`
+          xcrun simctl bootstatus $UDID -b
+
+      - name: Test
+        run: |
+          for TEST in `find tests/Release-iphonesimulator -depth 1 -name "*.app"`
+          do
+            xcrun simctl install booted $TEST
+            TEST_ID=`plutil -convert json -o - $TEST/Info.plist|jq -r ".CFBundleIdentifier"`
+            xcrun simctl launch --console booted $TEST_ID
+            xcrun simctl uninstall booted $TEST_ID
+          done

.travis.yml

@@ -12,9 +12,9 @@ cache:
     - ${TRAVIS_BUILD_DIR}/deps
 
 stages:
-  - name: Latest     # build jobs to run first and always
+  - name: Latest     # Compiler with the latest major version
+  - name: Previous   # Compilers with the major version Latest - 1
   - name: Validation # run other jobs
-  - name: Legacy     # build with all other supported compilers
 
 jobs:
   include:
@@ -62,73 +62,11 @@ jobs:
     # AppleClang on OSX
     ##########################################################################
 
-    # Xcode 8.3
-    - name: AppleClang Xcode-8.3 C++14 Debug
-      stage: Legacy
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode8.3
-    - name: AppleClang Xcode-8.3 C++14 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode8.3
 
-    # Xcode 9.0 earliest C++17 support
-    - name: AppleClang Xcode-9.0 C++17 Debug
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode9 # AppleClang 9.1.0 same compiler in Xcode 9.0, 9.1 and 9.2
-    - name: AppleClang Xcode-9.0 C++17 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode9
-    - name: AppleClang Xcode-9.0 C++14 Debug
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode9
-    - name: AppleClang Xcode-9.0 C++14 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode9
-
-    # Xcode 9.4
-    - name: AppleClang Xcode-9.4 C++14 Debug
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode9.4 # AppleClang 9.1.0 same compiler as Xcode 9.3
-    - name: AppleClang Xcode-9.4 C++14 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode9.4
-    - name: AppleClang Xcode-9.4 C++17 Debug
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode9.4
-    - name: AppleClang Xcode-9.4 C++17 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode9.4
-
-    # Xcode 10.1
-    - name: AppleClang Xcode-10.1 C++14 Debug
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode10.1 # AppleClang 10.0.0 same compiler as Xcode 10.0
-    - name: AppleClang Xcode-10.1 C++14 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      os: osx
-      osx_image: xcode10.1
-    - name: AppleClang Xcode-10.1 C++17 Debug
-      env: BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode10.1
-    - name: AppleClang Xcode-10.1 C++17 Release
-      env: BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      os: osx
-      osx_image: xcode10.1
 
     # 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
@@ -145,157 +83,33 @@ jobs:
       os: osx
       osx_image: xcode10.3
 
-    # Xcode 11.3
-    - name: AppleClang Xcode-11.3 C++17 Debug
+
+    # 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: xcode11.3 # AppleClang 11.0.0 linker update / same as Xcode 11.2
-    - name: AppleClang Xcode-11.3 C++17 Release
+      osx_image: xcode11.4
+    - name: AppleClang Xcode-11.4 C++17 Release
       env: BUILD_TYPE=Release GSL_CXX_STANDARD=17
       os: osx
-      osx_image: xcode11.3
-    - name: AppleClang Xcode-11.3 C++14 Debug
+      osx_image: xcode11.4
+    - name: AppleClang Xcode-11.4 C++14 Debug
       env: BUILD_TYPE=Debug GSL_CXX_STANDARD=14
       os: osx
-      osx_image: xcode11.3
-    - name: AppleClang Xcode-11.3 C++14 Release
+      osx_image: xcode11.4
+    - name: AppleClang Xcode-11.4 C++14 Release
       env: BUILD_TYPE=Release GSL_CXX_STANDARD=14
       os: osx
-      osx_image: xcode11.3
+      osx_image: xcode11.4
 
     ##########################################################################
     # Clang on Linux
     ##########################################################################
 
-    # Clang 3.6
-    - name: Clang-3.6 C++14 Debug
-      stage: Legacy
-      dist: xenial
-      env: CXX=clang++-3.6 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang36
-        apt:
-          packages:
-            - clang-3.6
-    - name: Clang-3.6 C++14 Release
-      dist: xenial
-      env: CXX=clang++-3.6 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang36
-
-    # Clang 3.7
-    - name: Clang-3.7 C++14 Debug
-      dist: xenial
-      env: CXX=clang++-3.7 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang37
-        apt:
-          packages:
-            - clang-3.7
-    - name: Clang-3.7 C++14 Release
-      dist: xenial
-      env: CXX=clang++-3.7 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang37
-
-    # Clang 3.8
-    - name: Clang-3.8 C++14 Debug
-      dist: xenial
-      env: CXX=clang++-3.8 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang38
-        apt:
-          packages:
-            - clang-3.8
-    - name: Clang-3.8 C++14 Release
-      dist: xenial
-      env: CXX=clang++-3.8 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang38
-
-    # Clang 3.9
-    - name: Clang-3.9 C++14 Debug
-      env: CXX=clang++-3.9 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang39
-        apt:
-          packages:
-            - clang-3.9
-    - name: Clang-3.9 C++14 Release
-      env: CXX=clang++-3.9 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang39
-
-    # Clang 4.0
-    - name: Clang-4.0 C++14 Debug
-      env: CXX=clang++-4.0 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang40
-        apt:
-          packages:
-            - clang-4.0
-    - name: Clang-4.0 C++14 Release
-      env: CXX=clang++-4.0 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang40
-
-    # Clang 5.0
-    - name: Clang-5.0 C++14 Debug
-      env: CXX=clang++-5.0 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang50
-        apt:
-          packages:
-            - clang-5.0
-    - name: Clang-5.0 C++14 Release
-      env: CXX=clang++-5.0 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang50
-    - name: Clang-5.0 C++17 Debug
-      env: CXX=clang++-5.0 BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      addons: *clang50
-    - name: Clang 5.0 C++17 Release
-      env: CXX=clang++-5.0 BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      addons: *clang50
-
-    # Clang 6.0
-    - name: Clang-6.0 C++14 Debug
-      env: CXX=clang++-6.0 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang60
-        apt:
-          packages:
-            - clang-6.0
-    - name: Clang 6.0 C++14 Release
-      env: CXX=clang++-6.0 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang60
-    - name: Clang-6.0 C++17 Debug
-      env: CXX=clang++-6.0 BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      addons: *clang60
-    - name: Clang 6.0 C++17 Release
-      env: CXX=clang++-6.0 BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      addons: *clang60
-
-    # Clang 7 (default on Xenial and Bionic images)
-    - name: Clang-7 C++14 Debug
-      env: CXX=clang++ BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-    - name: Clang-7 C++14 Release
-      env: CXX=clang++ BUILD_TYPE=Release GSL_CXX_STANDARD=14
-    - name: Clang-7 C++17 Debug
-      env: CXX=clang++ BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-    - name: Clang-7 C++17 Release
-      env: CXX=clang++ BUILD_TYPE=Release GSL_CXX_STANDARD=17
-
-    # Clang 8
-    - name: Clang-8 C++14 Debug
-      env: CXX=clang++-8 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &clang8
-        apt:
-          sources:
-          - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-8 main'
-            key_url: https://apt.llvm.org/llvm-snapshot.gpg.key
-          packages:
-          - clang-8
-    - name: Clang-8 C++14 Release
-      env: CXX=clang++-8 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *clang8
-    - name: Clang-8 C++17 Debug
-      env: CXX=clang++-8 BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-      addons: *clang8
-    - name: Clang-8 C++17 Release
-      env: CXX=clang++-8 BUILD_TYPE=Release GSL_CXX_STANDARD=17
-      addons: *clang8
-
     # Clang 9
     - name: Clang-9 C++14 Debug
+      stage: Previous
       env: CXX=clang++-9 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
       addons: &clang9
         apt:
@@ -339,37 +153,9 @@ jobs:
     # GCC on Linux
     ##########################################################################
 
-    # GCC 5 (default on the Xenial image)
-    - name: GCC-5 C++14 Debug
-      stage: Legacy
-      dist: xenial
-      env: CXX=g++-5 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-    - name: GCC-5 C++14 Release
-      dist: xenial
-      env: CXX=g++-5 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-
-    # GCC 6
-    - name: GCC-6 C++14 Debug
-      env: CXX=g++-6 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-      addons: &gcc6
-        apt:
-          packages: g++-6
-    - name: GCC-6 C++14 Release
-      env: CXX=g++-6 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-      addons: *gcc6
-
-    # GCC 7 (default on the Bionic image)
-    - name: GCC-7 C++14 Debug
-      env: CXX=g++-7 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
-    - name: GCC-7 C++14 Release
-      env: CXX=g++-7 BUILD_TYPE=Release GSL_CXX_STANDARD=14
-    - name: GCC-7 C++17 Debug
-      env: CXX=g++-7 BUILD_TYPE=Debug GSL_CXX_STANDARD=17
-    - name: GCC-7 C++17 Release
-      env: CXX=g++-7 BUILD_TYPE=Release GSL_CXX_STANDARD=17
-
     # GCC 8
     - name: GCC-8 C++14 Debug
+      stage: Previous
       env: CXX=g++-8 BUILD_TYPE=Debug GSL_CXX_STANDARD=14
       addons: &gcc8
         apt:
@@ -538,7 +324,7 @@ before_script:
   - |
     cd "${TRAVIS_BUILD_DIR:?}"
     mkdir build && cd build
-    if [[ ${GSL_CXX_STANDARD:-} ]]; then 
+    if [[ ${GSL_CXX_STANDARD:-} ]]; then
       CMAKE_GEN_FLAGS=("-DGSL_CXX_STANDARD=$GSL_CXX_STANDARD")
     fi
     CMAKE_GEN_FLAGS+=("-Wdev -Werror=dev --warn-uninitialized")

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.1.3...3.16)
 
-project(GSL CXX)
+project(GSL VERSION 3.1.0 LANGUAGES CXX)
 
 include(ExternalProject)
 find_package(Git)
@@ -14,7 +14,7 @@ add_library(GSL INTERFACE)
 # determine whether this is a standalone project or included by other projects
 set(GSL_STANDALONE_PROJECT OFF)
 if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
-  set(GSL_STANDALONE_PROJECT ON)
+    set(GSL_STANDALONE_PROJECT ON)
 endif ()
 
 set(GSL_CXX_STANDARD "14" CACHE STRING "Use c++ standard")
@@ -70,13 +70,13 @@ endif()
 
 if (CMAKE_VERSION VERSION_GREATER 3.7.8)
     if (MSVC_IDE)
-        option(VS_ADD_NATIVE_VISUALIZERS "Configure project to use Visual Studio native visualizers" TRUE)
+        option(GSL_VS_ADD_NATIVE_VISUALIZERS "Configure project to use Visual Studio native visualizers" TRUE)
     else()
-        set(VS_ADD_NATIVE_VISUALIZERS FALSE CACHE INTERNAL "Native visualizers are Visual Studio extension" FORCE)
+        set(GSL_VS_ADD_NATIVE_VISUALIZERS FALSE CACHE INTERNAL "Native visualizers are Visual Studio extension" FORCE)
     endif()
 
     # add natvis file to the library so it will automatically be loaded into Visual Studio
-    if(VS_ADD_NATIVE_VISUALIZERS)
+    if(GSL_VS_ADD_NATIVE_VISUALIZERS)
         target_sources(GSL INTERFACE
             $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/GSL.natvis>
         )
@@ -89,15 +89,39 @@ install(
     DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
 )
 # Make library importable by other projects
-install(EXPORT Microsoft.GSLConfig NAMESPACE Microsoft.GSL:: DESTINATION share/Microsoft.GSL/cmake)
+install(EXPORT Microsoft.GSLConfig NAMESPACE Microsoft.GSL:: DESTINATION ${CMAKE_INSTALL_DATADIR}/cmake/Microsoft.GSL)
 export(TARGETS GSL NAMESPACE Microsoft.GSL:: FILE Microsoft.GSLConfig.cmake)
 
+# Add find_package() versioning support. The version for
+# generated Microsoft.GSLConfigVersion.cmake will be used from
+# last project() command. The version's compatibility is set between all
+# minor versions (as it was in prev. GSL releases).
+include(CMakePackageConfigHelpers)
+if(${CMAKE_VERSION} VERSION_LESS "3.14.0")
+    write_basic_package_version_file(
+        ${CMAKE_CURRENT_BINARY_DIR}/Microsoft.GSLConfigVersion.cmake
+        COMPATIBILITY SameMajorVersion
+    )
+else()
+    write_basic_package_version_file(
+        ${CMAKE_CURRENT_BINARY_DIR}/Microsoft.GSLConfigVersion.cmake
+        COMPATIBILITY SameMajorVersion
+        ARCH_INDEPENDENT
+    )
+endif()
+install(FILES ${CMAKE_CURRENT_BINARY_DIR}/Microsoft.GSLConfigVersion.cmake DESTINATION ${CMAKE_INSTALL_DATADIR}/cmake/Microsoft.GSL)
+
 # Add Microsoft.GSL::GSL alias for GSL so that dependents can be agnostic about
 # whether GSL was added via `add_subdirectory` or `find_package`
 add_library(Microsoft.GSL::GSL ALIAS GSL)
 
 option(GSL_TEST "Generate tests." ${GSL_STANDALONE_PROJECT})
 if (GSL_TEST)
-	enable_testing()
-	add_subdirectory(tests)
+    enable_testing()
+    if(IOS)
+        add_compile_definitions(
+            GTEST_HAS_DEATH_TEST=1
+        )
+    endif()
+    add_subdirectory(tests)
 endif ()

GSL.natvis

@@ -19,9 +19,7 @@
         </Expand>
     </Type>
 
-    <!-- These types are from the span header. -->
-    <!-- This is for dynamic_extent spans. -->
-    <Type Name="gsl::span&lt;*, -1&gt;">
+    <Type Name="gsl::span&lt;*, *&gt;">
         <DisplayString>{{ extent = {storage_.size_} }}</DisplayString>
         <Expand>
             <ArrayItems>
@@ -31,43 +29,7 @@
         </Expand>
     </Type>
 
-    <!-- This works for constexpr size spans. -->
-    <Type Name="gsl::span&lt;*, *&gt;">
-        <DisplayString>{{ extent = {extent} }}</DisplayString>
-        <Expand>
-            <ArrayItems>
-                <Size>extent</Size>
-                <ValuePointer>storage_.data_</ValuePointer>
-            </ArrayItems>
-        </Expand>
-    </Type>
-
-    <!-- This is for dynamic_extent string_spans. -->
-    <Type Name="gsl::basic_string_span&lt;*, -1&gt;">
-        <DisplayString>{span_.storage_.data_,[span_.storage_.size_]na}</DisplayString>
-        <Expand>
-            <Item Name="[size]">span_.storage_.size_</Item>
-            <ArrayItems>
-                <Size>span_.storage_.size_</Size>
-                <ValuePointer>span_.storage_.data_</ValuePointer>
-            </ArrayItems>
-        </Expand>
-    </Type>
-
-    <!-- This works for constexpr size string_spans. -->
     <Type Name="gsl::basic_string_span&lt;*, *&gt;">
-        <DisplayString>{span_.storage_.data_,[span_.extent]na}</DisplayString>
-        <Expand>
-            <Item Name="[size]">span_.extent</Item>
-            <ArrayItems>
-                <Size>span_.extent</Size>
-                <ValuePointer>span_.storage_.data_</ValuePointer>
-            </ArrayItems>
-        </Expand>
-    </Type>
-
-    <!-- This is for dynamic_extent zstring_spans. -->
-    <Type Name="gsl::basic_zstring_span&lt;*, -1&gt;">
         <DisplayString>{span_.storage_.data_,[span_.storage_.size_]na}</DisplayString>
         <Expand>
             <Item Name="[size]">span_.storage_.size_</Item>
@@ -77,19 +39,18 @@
             </ArrayItems>
         </Expand>
     </Type>
-    
-    <!-- This works for constexpr size string_spans. -->
+
     <Type Name="gsl::basic_zstring_span&lt;*, *&gt;">
-        <DisplayString>{span_.storage_.data_,[span_.extent]na}</DisplayString>
+        <DisplayString>{span_.storage_.data_,[span_.storage_.size_]na}</DisplayString>
         <Expand>
-            <Item Name="[size]">span_.extent</Item>
+            <Item Name="[size]">span_.storage_.size_</Item>
             <ArrayItems>
-                <Size>span_.extent</Size>
+                <Size>span_.storage_.size_</Size>
                 <ValuePointer>span_.storage_.data_</ValuePointer>
             </ArrayItems>
         </Expand>
     </Type>
-    
+
     <!-- These types are from the gsl header. -->
     <Type Name="gsl::not_null&lt;*&gt;">
         <!-- We can always dereference this since it's an invariant. -->

README.md

@@ -1,12 +1,11 @@
-# GSL: Guidelines Support Library [![Build Status](https://travis-ci.org/Microsoft/GSL.svg?branch=master)](https://travis-ci.org/Microsoft/GSL) [![Build status](https://ci.appveyor.com/api/projects/status/github/Microsoft/GSL?svg=true)](https://ci.appveyor.com/project/neilmacintosh/GSL)
+# GSL: Guidelines Support Library
+[![Build Status](https://travis-ci.org/Microsoft/GSL.svg?branch=master)](https://travis-ci.org/Microsoft/GSL) [![Build status](https://ci.appveyor.com/api/projects/status/github/Microsoft/GSL?svg=true)](https://ci.appveyor.com/project/neilmacintosh/GSL)
 
 The Guidelines Support Library (GSL) contains functions and types that are suggested for use by the
 [C++ Core Guidelines](https://github.com/isocpp/CppCoreGuidelines) maintained by the [Standard C++ Foundation](https://isocpp.org).
 This repo contains Microsoft's implementation of GSL.
 
-The library includes types like `span<T>`, `string_span`, `owner<>` and others.
-
-The entire implementation is provided inline in the headers under the [gsl](./include/gsl) directory. The implementation generally assumes a platform that implements C++14 support. There are specific workarounds to support MSVC 2015.
+The entire implementation is provided inline in the headers under the [gsl](./include/gsl) directory. The implementation generally assumes a platform that implements C++14 support.
 
 While some types have been broken out into their own headers (e.g. [gsl/span](./include/gsl/span)),
 it is simplest to just include [gsl/gsl](./include/gsl/gsl) and gain access to the entire library.
@@ -20,35 +19,99 @@ This project has adopted the [Microsoft Open Source Code of Conduct](https://ope
 # Usage of Third Party Libraries
 This project makes use of the [Google Test](https://github.com/google/googletest) testing library. Please see the [ThirdPartyNotices.txt](./ThirdPartyNotices.txt) file for details regarding the licensing of Google Test.
 
+# Supported features
+## Microsoft GSL implements the following from the C++ Core Guidelines:
+
+Feature                            | Supported? | Description
+-----------------------------------|:----------:|-------------
+[**1. Views**][cg-views]           |            |
+owner                              | &#x2611;   | an alias for a raw pointer
+not_null                           | &#x2611;   | restricts a pointer / smart pointer to hold non-null values
+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
+[**2. Owners**][cg-owners]         |            |
+unique_ptr                         | &#x2611;   | an alias to `std::unique_ptr`
+shared_ptr                         | &#x2611;   | an alias to `std::shared_ptr`
+stack_array                        | &#x2610;   | a stack-allocated array
+dyn_array                          | &#x2610;   | a heap-allocated array
+[**3. Assertions**][cg-assertions] |            |
+Expects                            | &#x2611;   | a precondition assertion; on failure it terminates
+Ensures                            | &#x2611;   | a postcondition assertion; on failure it terminates
+[**4. Utilities**][cg-utilities]   |            |
+move_owner                         | &#x2610;   | a helper function that moves one `owner` to the other
+byte                               | &#x2611;   | either an alias to std::byte or a byte type
+final_action                       | &#x2611;   | a RAII style class that invokes a functor on its destruction
+finally                            | &#x2611;   | a helper function instantiating `final_action`
+GSL_SUPPRESS                       | &#x2611;   | a macro that takes an argument and turns it into `[[gsl::suppress(x)]]` or `[[gsl::suppress("x")]]`
+[[implicit]]                       | &#x2610;   | a "marker" to put on single-argument constructors to explicitly make them non-explicit
+index                              | &#x2611;   | a type to use for all container and array indexing (currently an alias for std::ptrdiff_t)
+joining_thread                     | &#x2610;   | a RAII style version of `std::thread` that joins
+narrow                             | &#x2611;   | a checked version of narrow_cast; it can throw `narrowing_error`
+narrow_cast                        | &#x2611;   | a narrowing cast for values and a synonym for static_cast
+narrowing_error                    | &#x2611;   | a custom exception type thrown by `narrow()`
+[**5. Concepts**][cg-concepts]     | &#x2610;   |
+
+## The following features do not exist in or have been removed from the C++ Core Guidelines:
+Feature                            | Supported? | Description
+-----------------------------------|:----------:|-------------
+strict_not_null                    | &#x2611;   | A stricter version of `not_null` with explicit constructors
+multi_span                         | &#x2610;   | Deprecated. Multi-dimensional span.
+strided_span                       | &#x2610;   | Deprecated. Support for this type has been discontinued.
+basic_zstring                      | &#x2610;   | Deprecated. A pointer to a C-string (zero-terminated array) with a templated char type
+zstring                            | &#x2610;   | Deprecated. An alias to `basic_zstring` with a char type of char
+czstring                           | &#x2610;   | Deprecated. An alias to `basic_zstring` with a char type of const char
+wzstring                           | &#x2610;   | Deprecated. An alias to `basic_zstring` with a char type of wchar_t
+cwzstring                          | &#x2610;   | Deprecated. An alias to `basic_zstring` with a char type of const wchar_t
+u16zstring                         | &#x2610;   | Deprecated. An alias to `basic_zstring` with a char type of char16_t
+cu16zstring                        | &#x2610;   | Deprecated. An alias to `basic_zstring` with a char type of const char16_t
+u32zstring                         | &#x2610;   | Deprecated. An alias to `basic_zstring` with a char type of char32_t
+cu32zstring                        | &#x2610;   | Deprecated. An alias to `basic_zstring` with a char type of const char32_t
+basic_string_span                  | &#x2610;   | Deprecated. Like `span` but for strings with a templated char type
+string_span                        | &#x2610;   | Deprecated. An alias to `basic_string_span` with a char type of char
+cstring_span                       | &#x2610;   | Deprecated. An alias to `basic_string_span` with a char type of const char
+wstring_span                       | &#x2610;   | Deprecated. An alias to `basic_string_span` with a char type of wchar_t
+cwstring_span                      | &#x2610;   | Deprecated. An alias to `basic_string_span` with a char type of const wchar_t
+u16string_span                     | &#x2610;   | Deprecated. An alias to `basic_string_span` with a char type of char16_t
+cu16string_span                    | &#x2610;   | Deprecated. An alias to `basic_string_span` with a char type of const char16_t
+u32string_span                     | &#x2610;   | Deprecated. An alias to `basic_string_span` with a char type of char32_t
+cu32string_span                    | &#x2610;   | Deprecated. An alias to `basic_string_span` with a char type of const char32_t
+
+This is based on [CppCoreGuidelines semi-specification](https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#gsl-guidelines-support-library).
+
+[cg-views]: https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#gslview-views
+[cg-owners]: https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#gslowner-ownership-pointers
+[cg-assertions]: https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#gslassert-assertions
+[cg-utilities]: https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#gslutil-utilities
+[cg-concepts]: https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#gslconcept-concepts
+
 # Quick Start
-## Supported Platforms
-The test suite that exercises GSL has been built and passes successfully on the following platforms:<sup>1)</sup>
+## 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.
 
-* Windows using Visual Studio 2015
-* Windows using Visual Studio 2017
-* Windows using Clang/LLVM 3.6
-* Windows using Clang/LLVM 7.0.0
-* Windows using GCC 5.1
-* Windows using Intel C++ Compiler 18.0
-* GNU/Linux using Clang/LLVM 3.6-3.9
-* GNU/Linux using Clang/LLVM 4.0
-* GNU/Linux using Clang/LLVM 5.0
-* GNU/Linux using Clang/LLVM 6.0
-* GNU/Linux using Clang/LLVM 7.0
-* GNU/Linux using GCC 5.1
-* OS X Mojave 10.14.4 using Apple LLVM version 10.0.0 (10.0.1.10010046)
-* OS X Mojave 10.14.3 using Apple LLVM version 10.0.0 (clang-1000.11.45.5)
-* OS X Yosemite using Xcode with Apple Clang 7.0.0.7000072
-* OS X Yosemite using GCC-5.2.0
-* OS X Sierra 10.12.4 using Apple LLVM version 8.1.0 (Clang-802.0.42)
-* OS X El Capitan (10.11) using Xcode with AppleClang 8.0.0.8000042
-* OS X High Sierra 10.13.2 (17C88) using Apple LLVM version 9.0.0 (clang-900.0.39.2)
-* FreeBSD 10.x with Clang/LLVM 3.6
+Compiler |Toolset Versions Currently Tested| Build Status
+:------- |:--|------------:
+ XCode |11.4 & 10.3 | [![Status](https://travis-ci.org/Microsoft/GSL.svg?branch=master)](https://travis-ci.org/Microsoft/GSL)
+ GCC |9 & 8| [![Status](https://travis-ci.org/Microsoft/GSL.svg?branch=master)](https://travis-ci.org/Microsoft/GSL)
+ Clang |11 &  10| [![Status](https://travis-ci.org/Microsoft/GSL.svg?branch=master)](https://travis-ci.org/Microsoft/GSL)
+ Visual Studio with MSVC | VS2017 (15.9) & VS2019 (16.4) | [![Status](https://ci.appveyor.com/api/projects/status/github/Microsoft/GSL?svg=true)](https://ci.appveyor.com/project/neilmacintosh/GSL)
+ Visual Studio with LLVM | VS2017 (Clang 9) & VS2019 (Clang 10) | [![Status](https://ci.appveyor.com/api/projects/status/github/Microsoft/GSL?svg=true)](https://ci.appveyor.com/project/neilmacintosh/GSL)
 
-> If you successfully port GSL to another platform, we would love to hear from you. Please submit an issue to let us know. Also please consider
-contributing any changes that were necessary back to this project to benefit the wider community.
 
-<sup>1)</sup> For `gsl::byte` to work correctly with Clang and GCC you might have to use the ` -fno-strict-aliasing` compiler option.
+Note: For `gsl::byte` to work correctly with Clang and GCC you might have to use the ` -fno-strict-aliasing` compiler option.
+
+---
+If you successfully port GSL to another platform, we would love to hear from you!
+- Submit an issue specifying the platform and target.
+- Consider contributing your changes by filing a pull request with any necessary changes.
+- If at all possible, add a CI/CD step and add the button to the table below!
+
+Target | CI/CD Status
+:------- | -----------:
+iOS | ![CI_iOS](https://github.com/microsoft/GSL/workflows/CI_iOS/badge.svg)
+Android | ![CI_Android](https://github.com/microsoft/GSL/workflows/CI_Android/badge.svg)
+
+Note: These CI/CD steps are run with each pull request, however failures in them are non-blocking.
 
 ## Building the tests
 To build the tests, you will require the following:
@@ -65,7 +128,7 @@ These steps assume the source code of this repository has been cloned into a dir
 
 2. Configure CMake to use the compiler of your choice (you can see a list by running `cmake --help`).
 
-        cmake -G "Visual Studio 14 2015" c:\GSL
+        cmake -G "Visual Studio 15 2017" c:\GSL
 
 3. Build the test suite (in this case, in the Debug configuration, Release is another good choice).
 

appveyor.yml

@@ -9,7 +9,6 @@ configuration:
   - Release
 
 image:
-  - Visual Studio 2015
   - Visual Studio 2017
   - Visual Studio 2019
 
@@ -17,7 +16,6 @@ environment:
   NINJA_TAG: v1.8.2
   NINJA_SHA512: 9B9CE248240665FCD6404B989F3B3C27ED9682838225E6DC9B67B551774F251E4FF8A207504F941E7C811E7A8BE1945E7BCB94472A335EF15E23A0200A32E6D5
   NINJA_PATH: C:\Tools\ninja\ninja-%NINJA_TAG%
-  VCVAR2015: 'C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat'
   VCVAR2017: 'C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvarsall.bat'
   VCVAR2019: 'C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat'
   matrix:
@@ -34,14 +32,6 @@ environment:
       USE_TOOLSET: LLVM
       USE_GENERATOR: Ninja
 
-matrix:
-    exclude:
-    - image: Visual Studio 2015
-      GSL_CXX_STANDARD: 17
-    - image: Visual Studio 2015
-      USE_TOOLSET: LLVM
-      USE_GENERATOR: MSBuild
-
 cache:
   - C:\cmake-3.14.4-win32-x86
   - C:\Tools\ninja
@@ -72,9 +62,7 @@ before_build:
       if ("$env:USE_GENERATOR" -eq "Ninja") {
         $GeneratorFlags = '-k 10'
         $Architecture = $env:PLATFORM
-        if ("$env:APPVEYOR_BUILD_WORKER_IMAGE" -eq "Visual Studio 2015") {
-          $env:VCVARSALL = "`"$env:VCVAR2015`" $Architecture"
-        } elseif ("$env:APPVEYOR_BUILD_WORKER_IMAGE" -eq "Visual Studio 2017") {
+        if ("$env:APPVEYOR_BUILD_WORKER_IMAGE" -eq "Visual Studio 2017") {
           $env:VCVARSALL = "`"$env:VCVAR2017`" $Architecture"
         } else {
           $env:VCVARSALL = "`"$env:VCVAR2019`" $Architecture"
@@ -82,17 +70,15 @@ before_build:
         $env:CMakeGenFlags = "-G Ninja -DGSL_CXX_STANDARD=$env:GSL_CXX_STANDARD"
       } else {
         $GeneratorFlags = '/m /v:minimal'
-        if ("$env:APPVEYOR_BUILD_WORKER_IMAGE" -eq "Visual Studio 2015") {
-          $Generator = 'Visual Studio 14 2015'
-        } elseif ("$env:APPVEYOR_BUILD_WORKER_IMAGE" -eq "Visual Studio 2017") {
+        if ("$env:APPVEYOR_BUILD_WORKER_IMAGE" -eq "Visual Studio 2017") {
           $Generator = 'Visual Studio 15 2017'
         } else {
           $Generator = 'Visual Studio 16 2019'
         }
-        if ("$env:PLATFORM" -eq "x86") { 
+        if ("$env:PLATFORM" -eq "x86") {
             $Architecture = "Win32"
-        } else { 
-            $Architecture = "x64" 
+        } else {
+            $Architecture = "x64"
         }
         if ("$env:USE_TOOLSET" -eq "LLVM") {
           $env:CMakeGenFlags = "-G `"$Generator`" -A $Architecture -T llvm -DGSL_CXX_STANDARD=$env:GSL_CXX_STANDARD"

include/gsl/gsl_assert

@@ -45,7 +45,7 @@
 #if defined(__clang__)
 #define GSL_SUPPRESS(x) [[gsl::suppress("x")]]
 #else
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) && ! defined(__INTEL_COMPILER)
 #define GSL_SUPPRESS(x) [[gsl::suppress(x)]]
 #else
 #define GSL_SUPPRESS(x)

include/gsl/gsl_byte

@@ -24,7 +24,7 @@
 #if defined(__clang__)
 #define GSL_SUPPRESS(x) [[gsl::suppress("x")]]
 #else
-#if defined(_MSC_VER)
+#if defined(_MSC_VER) && ! defined(__INTEL_COMPILER)
 #define GSL_SUPPRESS(x) [[gsl::suppress(x)]]
 #else
 #define GSL_SUPPRESS(x)
@@ -59,8 +59,8 @@
 
 #ifndef GSL_USE_STD_BYTE
 #include <cstddef> /* __cpp_lib_byte */
-// this tests if we are under GCC or Clang with enough -std:c++1z power to get us std::byte
-// also check if libc++ version is sufficient (> 5.0) or libstc++ actually contains std::byte
+// this tests if we are under GCC or Clang with enough -std=c++1z power to get us std::byte
+// also check if libc++ version is sufficient (> 5.0) or libstdc++ actually contains std::byte
 #if defined(__cplusplus) && (__cplusplus >= 201703L) && \
   (defined(__cpp_lib_byte) && (__cpp_lib_byte >= 201603)  || \
    defined(_LIBCPP_VERSION) && (_LIBCPP_VERSION >= 5000))

include/gsl/gsl_narrow

@@ -0,0 +1,52 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
+//
+// This code is licensed under the MIT License (MIT).
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef GSL_NARROW_H
+#define GSL_NARROW_H
+#include <gsl/gsl_assert> // for Expects
+#include <gsl/gsl_util> // for narrow_cast
+namespace gsl
+{
+struct narrowing_error : public std::exception
+{
+    const char* what() const noexcept override
+    {
+        return "narrowing_error";
+    }
+};
+
+// narrow() : a checked version of narrow_cast() that throws if the cast changed the value
+template <class T, class U>
+GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recognise noexcept(false)
+constexpr
+T narrow(U u) noexcept(false)
+{
+    constexpr const bool is_different_signedness = (std::is_signed<T>::value != std::is_signed<U>::value);
+
+    const T t = narrow_cast<T>(u);
+
+    if (static_cast<U>(t) != u
+        || (is_different_signedness
+            && ((t < T{}) != (u < U{}))))
+    {
+        throw narrowing_error{};
+    }
+
+    return t;
+}
+}
+#endif // GSL_NARROW_H

include/gsl/gsl_util

@@ -30,17 +30,13 @@
 #pragma warning(push)
 #pragma warning(disable : 4127) // conditional expression is constant
 
-#if _MSC_VER < 1910
-#pragma push_macro("constexpr")
-#define constexpr /*constexpr*/
-#endif            // _MSC_VER < 1910
 #endif            // _MSC_VER
 
-#if (defined(_MSC_VER) && _MSC_VER < 1910) || (!defined(__clang__) && defined(__GNUC__) && __GNUC__ < 6)
-#define GSL_CONSTEXPR_NARROW 0
+#if defined(__cplusplus) && (__cplusplus >= 201703L)
+#define GSL_NODISCARD [[nodiscard]]
 #else
-#define GSL_CONSTEXPR_NARROW 1
-#endif
+#define GSL_NODISCARD
+#endif // defined(__cplusplus) && (__cplusplus >= 201703L)
 
 namespace gsl
 {
@@ -56,6 +52,8 @@ template <class F>
 class final_action
 {
 public:
+    static_assert(!std::is_reference<F>::value && !std::is_const<F>::value && !std::is_volatile<F>::value, "Final_action should store its callable by value");
+
     explicit final_action(F f) noexcept : f_(std::move(f)) {}
 
     final_action(final_action&& other) noexcept : f_(std::move(other.f_)), invoke_(std::exchange(other.invoke_, false)) {}
@@ -77,15 +75,9 @@ private:
 
 // finally() - convenience function to generate a final_action
 template <class F>
-final_action<F> finally(const F& f) noexcept
+GSL_NODISCARD final_action<typename std::remove_cv<typename std::remove_reference<F>::type>::type> finally(F&& f) noexcept
 {
-    return final_action<F>(f);
-}
-
-template <class F>
-final_action<F> finally(F&& f) noexcept
-{
-    return final_action<F>(std::forward<F>(f));
+    return final_action<typename std::remove_cv<typename std::remove_reference<F>::type>::type>(std::forward<F>(f));
 }
 
 // narrow_cast(): a searchable way to do narrowing casts of values
@@ -96,31 +88,6 @@ constexpr T narrow_cast(U&& u) noexcept
     return static_cast<T>(std::forward<U>(u));
 }
 
-namespace details
-{
-    template <class T, class U>
-    struct is_same_signedness
-        : public std::integral_constant<bool, std::is_signed<T>::value == std::is_signed<U>::value>
-    {
-    };
-} // namespace details
-
-// narrow() : a checked version of narrow_cast() that throws if the cast changed the value
-template <class T, class U>
-GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
-GSL_SUPPRESS(f.6) // NO-FORMAT: attribute // TODO: MSVC /analyze does not recognise noexcept(false)
-#if GSL_CONSTEXPR_NARROW
-constexpr
-#endif
-T narrow(U u) noexcept(false)
-{
-    T t = narrow_cast<T>(u);
-    if (static_cast<U>(t) != u) gsl::details::terminate();
-    if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{})))
-        gsl::details::terminate();
-    return t;
-}
-
 //
 // at() - Bounds-checked way of accessing builtin arrays, std::array, std::vector
 //
@@ -154,11 +121,6 @@ constexpr T at(const std::initializer_list<T> cont, const index i)
 } // namespace gsl
 
 #if defined(_MSC_VER) && !defined(__clang__)
-#if _MSC_VER < 1910
-#undef constexpr
-#pragma pop_macro("constexpr")
-
-#endif // _MSC_VER < 1910
 
 #pragma warning(pop)
 

include/gsl/multi_span

@@ -23,7 +23,7 @@
 
 #include <algorithm> // for transform, lexicographical_compare
 #include <array>     // for array
-#include <cstddef>          // for ptrdiff_t, size_t, nullptr_t
+#include <cstddef>          // for std::ptrdiff_t, size_t, nullptr_t
 #include <cstdint>          // for PTRDIFF_MAX
 #include <functional>       // for divides, multiplies, minus, negate, plus
 #include <initializer_list> // for initializer_list
@@ -50,11 +50,6 @@
 #pragma warning(disable : 26465) // TODO: bug - suppression does not work on template functions
 #pragma warning(disable : 4996)  // use of function or classes marked [[deprecated]]
 
-#if _MSC_VER < 1910
-#pragma push_macro("constexpr")
-#define constexpr /*constexpr*/
-
-#endif // _MSC_VER < 1910
 #endif // _MSC_VER
 
 #if defined(__GNUC__) || defined(__clang__)
@@ -62,7 +57,7 @@
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 #endif
 
-// GCC 7 does not like the signed unsigned missmatch (size_t ptrdiff_t)
+// GCC 7 does not like the signed unsigned missmatch (size_t std::ptrdiff_t)
 // While there is a conversion from signed to unsigned, it happens at
 // compiletime, so the compiler wouldn't have to warn indiscriminently, but
 // could check if the source value actually doesn't fit into the target type
@@ -392,9 +387,9 @@ namespace details
         template <typename T, std::size_t Dim = 0>
         constexpr size_type contains(const T& arr) const
         {
-            const ptrdiff_t last = this->Base::template contains<T, Dim + 1>(arr);
+            const std::ptrdiff_t last = this->Base::template contains<T, Dim + 1>(arr);
             if (last == -1) return -1;
-            const ptrdiff_t cur = this->Base::totalSize() * arr[Dim];
+            const std::ptrdiff_t cur = this->Base::totalSize() * arr[Dim];
             return cur < m_bound ? cur + last : -1;
         }
 
@@ -462,7 +457,7 @@ namespace details
             GSL_SUPPRESS(bounds.4)                            // NO-FORMAT: attribute
             Expects(arr[Dim] >= 0 && arr[Dim] < CurrentRange); // Index is out of range
             GSL_SUPPRESS(bounds.4)                            // NO-FORMAT: attribute
-            const ptrdiff_t d = arr[Dim];
+            const std::ptrdiff_t d = arr[Dim];
             return this->Base::totalSize() * d + this->Base::template linearize<T, Dim + 1>(arr);
         }
 
@@ -2252,11 +2247,6 @@ general_span_iterator<Span> operator+(typename general_span_iterator<Span>::diff
 } // namespace gsl
 
 #if defined(_MSC_VER) && !defined(__clang__)
-#if _MSC_VER < 1910
-
-#undef constexpr
-#pragma pop_macro("constexpr")
-#endif // _MSC_VER < 1910
 
 #pragma warning(pop)
 

include/gsl/pointers

@@ -25,12 +25,6 @@
 #include <system_error> // for hash
 #include <type_traits>  // for enable_if_t, is_convertible, is_assignable
 
-#if defined(_MSC_VER) && _MSC_VER < 1910 && !defined(__clang__)
-#pragma push_macro("constexpr")
-#define constexpr /*constexpr*/
-
-#endif                          // defined(_MSC_VER) && _MSC_VER < 1910
-
 namespace gsl
 {
 
@@ -69,7 +63,7 @@ template <class T>
 class not_null
 {
 public:
-    static_assert(std::is_assignable<T&, std::nullptr_t>::value, "T cannot be assigned nullptr.");
+    static_assert(std::is_convertible<decltype(std::declval<T>() != nullptr), bool>::value, "T cannot be compared to nullptr.");
 
     template <typename U, typename = std::enable_if_t<std::is_convertible<U, T>::value>>
     constexpr not_null(U&& u) : ptr_(std::forward<U>(u))
@@ -78,7 +72,7 @@ public:
     }
 
     template <typename = std::enable_if_t<!std::is_same<std::nullptr_t, T>::value>>
-    constexpr not_null(T u) : ptr_(u)
+    constexpr not_null(T u) : ptr_(std::move(u))
     {
         Expects(ptr_ != nullptr);
     }
@@ -90,15 +84,14 @@ public:
 
     not_null(const not_null& other) = default;
     not_null& operator=(const not_null& other) = default;
-
-    constexpr T get() const
+    constexpr std::conditional_t<std::is_copy_constructible<T>::value, T, const T&> get() const
     {
         Ensures(ptr_ != nullptr);
         return ptr_;
     }
 
     constexpr operator T() const { return get(); }
-    constexpr T operator->() const { return get(); }
+    constexpr decltype(auto) operator->() const { return get(); }
     constexpr decltype(auto) operator*() const { return *get(); }
 
     // prevents compilation when someone attempts to assign a null pointer constant
@@ -119,7 +112,7 @@ private:
 };
 
 template <class T>
-auto make_not_null(T&& t) {
+auto make_not_null(T&& t) noexcept {
     return not_null<std::remove_cv_t<std::remove_reference_t<T>>>{std::forward<T>(t)};
 }
 
@@ -131,37 +124,37 @@ std::ostream& operator<<(std::ostream& os, const not_null<T>& val)
 }
 
 template <class T, class U>
-auto operator==(const not_null<T>& lhs, const not_null<U>& rhs) -> decltype(lhs.get() == rhs.get())
+auto operator==(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() == rhs.get())) -> decltype(lhs.get() == rhs.get())
 {
     return lhs.get() == rhs.get();
 }
 
 template <class T, class U>
-auto operator!=(const not_null<T>& lhs, const not_null<U>& rhs) -> decltype(lhs.get() != rhs.get())
+auto operator!=(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() != rhs.get())) -> decltype(lhs.get() != rhs.get())
 {
     return lhs.get() != rhs.get();
 }
 
 template <class T, class U>
-auto operator<(const not_null<T>& lhs, const not_null<U>& rhs) -> decltype(lhs.get() < rhs.get())
+auto operator<(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() < rhs.get())) -> decltype(lhs.get() < rhs.get())
 {
     return lhs.get() < rhs.get();
 }
 
 template <class T, class U>
-auto operator<=(const not_null<T>& lhs, const not_null<U>& rhs) -> decltype(lhs.get() <= rhs.get())
+auto operator<=(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() <= rhs.get())) -> decltype(lhs.get() <= rhs.get())
 {
     return lhs.get() <= rhs.get();
 }
 
 template <class T, class U>
-auto operator>(const not_null<T>& lhs, const not_null<U>& rhs) -> decltype(lhs.get() > rhs.get())
+auto operator>(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() > rhs.get())) -> decltype(lhs.get() > rhs.get())
 {
     return lhs.get() > rhs.get();
 }
 
 template <class T, class U>
-auto operator>=(const not_null<T>& lhs, const not_null<U>& rhs) -> decltype(lhs.get() >= rhs.get())
+auto operator>=(const not_null<T>& lhs, const not_null<U>& rhs) noexcept(noexcept(lhs.get() >= rhs.get())) -> decltype(lhs.get() >= rhs.get())
 {
     return lhs.get() >= rhs.get();
 }
@@ -183,7 +176,7 @@ namespace std
 template <class T>
 struct hash<gsl::not_null<T>>
 {
-    std::size_t operator()(const gsl::not_null<T>& value) const { return hash<T>{}(value); }
+    std::size_t operator()(const gsl::not_null<T>& value) const { return hash<T>{}(value.get()); }
 };
 
 } // namespace std
@@ -267,7 +260,7 @@ template <class T>
 strict_not_null<T> operator+(std::ptrdiff_t, const strict_not_null<T>&) = delete;
 
 template <class T>
-auto make_strict_not_null(T&& t) {
+auto make_strict_not_null(T&& t) noexcept {
     return strict_not_null<std::remove_cv_t<std::remove_reference_t<T>>>{std::forward<T>(t)};
 }
 
@@ -286,16 +279,9 @@ namespace std
 template <class T>
 struct hash<gsl::strict_not_null<T>>
 {
-    std::size_t operator()(const gsl::strict_not_null<T>& value) const { return hash<T>{}(value); }
+    std::size_t operator()(const gsl::strict_not_null<T>& value) const { return hash<T>{}(value.get()); }
 };
 
 } // namespace std
 
-#if defined(_MSC_VER) && _MSC_VER < 1910 && !defined(__clang__)
-
-#undef constexpr
-#pragma pop_macro("constexpr")
-
-#endif // defined(_MSC_VER) && _MSC_VER < 1910 && !defined(__clang__)
-
 #endif // GSL_POINTERS_H

include/gsl/span

@@ -19,7 +19,7 @@
 
 #include <gsl/gsl_assert> // for Expects
 #include <gsl/gsl_byte>   // for byte
-#include <gsl/gsl_util>   // for narrow_cast, narrow
+#include <gsl/gsl_util>   // for narrow_cast
 
 #include <array>       // for array
 #include <cstddef>     // for ptrdiff_t, size_t, nullptr_t
@@ -39,12 +39,6 @@
 #pragma warning(disable : 26495) // uninitalized member when constructor calls constructor
 #pragma warning(disable : 26446) // parser bug does not allow attributes on some templates
 
-#if _MSC_VER < 1910
-#pragma push_macro("constexpr")
-#define constexpr /*constexpr*/
-#define GSL_USE_STATIC_CONSTEXPR_WORKAROUND
-
-#endif // _MSC_VER < 1910
 #endif // _MSC_VER
 
 // See if we have enough C++17 power to use a static constexpr data member
@@ -67,7 +61,7 @@ namespace gsl
 {
 
 // [views.constants], constants
-constexpr const std::size_t dynamic_extent = static_cast<std::size_t>(-1);
+constexpr const std::size_t dynamic_extent = narrow_cast<std::size_t>(-1);
 
 template <class ElementType, std::size_t Extent = dynamic_extent>
 class span;
@@ -107,7 +101,7 @@ namespace details
 
     template <std::size_t From, std::size_t To>
     struct is_allowed_extent_conversion
-        : std::integral_constant<bool, From == To || To == gsl::dynamic_extent>
+        : std::integral_constant<bool, From == To || To == dynamic_extent>
     {
     };
 
@@ -344,17 +338,18 @@ namespace details
 
         constexpr extent_type() noexcept = default;
 
-        template <size_type Other>
-        constexpr extent_type(extent_type<Other> ext)
-        {
-            static_assert(Other == Ext,
-                          "Mismatch between fixed-size extent and size of initializing data.");
-            Expects(ext.size() == Ext);
-        }
+        constexpr explicit extent_type(extent_type<dynamic_extent>);
 
-        constexpr extent_type(size_type size) { Expects(size == Ext); }
+        constexpr explicit extent_type(size_type size) { Expects(size == Ext); }
 
         constexpr size_type size() const noexcept { return Ext; }
+
+    private:
+#if defined(GSL_USE_STATIC_CONSTEXPR_WORKAROUND)
+        static constexpr const size_type size_ = Ext; // static size equal to Ext
+#else
+        static constexpr size_type size_ = Ext; // static size equal to Ext
+#endif
     };
 
     template <>
@@ -364,10 +359,10 @@ namespace details
         using size_type = std::size_t;
 
         template <size_type Other>
-        explicit constexpr extent_type(extent_type<Other> ext) : size_(ext.size())
+        constexpr explicit extent_type(extent_type<Other> ext) : size_(ext.size())
         {}
 
-        explicit constexpr extent_type(size_type size) : size_(size)
+        constexpr explicit extent_type(size_type size) : size_(size)
         {
             Expects(size != dynamic_extent);
         }
@@ -378,6 +373,12 @@ namespace details
         size_type size_;
     };
 
+    template <std::size_t Ext>
+    constexpr extent_type<Ext>::extent_type(extent_type<dynamic_extent> ext)
+    {
+        Expects(ext.size() == Ext);
+    }
+
     template <class ElementType, std::size_t Extent, std::size_t Offset, std::size_t Count>
     struct calculate_subspan_type
     {
@@ -421,18 +422,28 @@ public:
     constexpr span() noexcept : storage_(nullptr, details::extent_type<0>())
     {}
 
-    constexpr span(pointer ptr, size_type count) noexcept : storage_(ptr, count)
+    template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent != dynamic_extent, int> = 0>
+    constexpr explicit span(pointer ptr, size_type count) noexcept : storage_(ptr, count)
     {
-        if (Extent != dynamic_extent) Expects(count == Extent);
+        Expects(count == Extent);
     }
 
-    constexpr span(pointer firstElem, pointer lastElem) noexcept
-        : storage_(firstElem, static_cast<std::size_t>(lastElem - firstElem))
+    template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent == dynamic_extent, int> = 0>
+    constexpr span(pointer ptr, size_type count) noexcept : storage_(ptr, count)
+    {}
+
+    template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent != dynamic_extent, int> = 0>
+    constexpr explicit span(pointer firstElem, pointer lastElem) noexcept
+        : storage_(firstElem, narrow_cast<std::size_t>(lastElem - firstElem))
     {
-        if (Extent != dynamic_extent)
-        { Expects(lastElem - firstElem == static_cast<difference_type>(Extent)); }
+        Expects(lastElem - firstElem == static_cast<difference_type>(Extent));
     }
 
+    template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent == dynamic_extent, int> = 0>
+    constexpr span(pointer firstElem, pointer lastElem) noexcept
+        : storage_(firstElem, narrow_cast<std::size_t>(lastElem - firstElem))
+    {}
+
     template <std::size_t N,
               std::enable_if_t<details::is_allowed_extent_conversion<N, Extent>::value, int> = 0>
     constexpr span(element_type (&arr)[N]) noexcept
@@ -457,40 +468,74 @@ public:
         : storage_(KnownNotNull{arr.data()}, details::extent_type<N>())
     {}
 
-    // NB: the SFINAE here uses .data() as an incomplete/imperfect proxy for the requirement
-    // on Container to be a contiguous sequence container.
-    template <class Container,
-              class = std::enable_if_t<
+    // NB: the SFINAE on these constructors uses .data() as an incomplete/imperfect proxy for the
+    // requirement on Container to be a contiguous sequence container.
+    template <std::size_t MyExtent = Extent, class Container,
+              std::enable_if_t<
+                  MyExtent != dynamic_extent &&
                   !details::is_span<Container>::value && !details::is_std_array<Container>::value &&
                   std::is_pointer<decltype(std::declval<Container&>().data())>::value &&
                   std::is_convertible<
                       std::remove_pointer_t<decltype(std::declval<Container&>().data())> (*)[],
-                      element_type (*)[]>::value>>
+                      element_type (*)[]>::value, int> = 0>
+    constexpr explicit span(Container& cont) noexcept : span(cont.data(), cont.size())
+    {}
+
+    template <std::size_t MyExtent = Extent, class Container,
+              std::enable_if_t<
+                  MyExtent == dynamic_extent &&
+                  !details::is_span<Container>::value && !details::is_std_array<Container>::value &&
+                  std::is_pointer<decltype(std::declval<Container&>().data())>::value &&
+                  std::is_convertible<
+                      std::remove_pointer_t<decltype(std::declval<Container&>().data())> (*)[],
+                      element_type (*)[]>::value, int> = 0>
     constexpr span(Container& cont) noexcept : span(cont.data(), cont.size())
     {}
 
-    template <class Container,
-              class = std::enable_if_t<
+    template <std::size_t MyExtent = Extent, class Container,
+              std::enable_if_t<
+                  MyExtent != dynamic_extent &&
                   std::is_const<element_type>::value && !details::is_span<Container>::value &&
                   !details::is_std_array<Container>::value &&
                   std::is_pointer<decltype(std::declval<const Container&>().data())>::value &&
                   std::is_convertible<std::remove_pointer_t<
-                                          decltype(std::declval<const Container&>().data())> (*)[],
-                                      element_type (*)[]>::value>>
+                      decltype(std::declval<const Container&>().data())> (*)[],
+                      element_type (*)[]>::value, int> = 0>
+    constexpr explicit span(const Container& cont) noexcept : span(cont.data(), cont.size())
+    {}
+
+    template <std::size_t MyExtent = Extent, class Container,
+              std::enable_if_t<
+                  MyExtent == dynamic_extent &&
+                  std::is_const<element_type>::value && !details::is_span<Container>::value &&
+                  !details::is_std_array<Container>::value &&
+                  std::is_pointer<decltype(std::declval<const Container&>().data())>::value &&
+                  std::is_convertible<std::remove_pointer_t<
+                      decltype(std::declval<const Container&>().data())> (*)[],
+                      element_type (*)[]>::value, int> = 0>
     constexpr span(const Container& cont) noexcept : span(cont.data(), cont.size())
     {}
 
     constexpr span(const span& other) noexcept = default;
 
     template <
-        class OtherElementType, std::size_t OtherExtent,
-        class = std::enable_if_t<
-            details::is_allowed_extent_conversion<OtherExtent, Extent>::value &&
-            details::is_allowed_element_type_conversion<OtherElementType, element_type>::value>>
+        class OtherElementType, std::size_t OtherExtent, std::size_t MyExtent = Extent,
+        std::enable_if_t<
+            (MyExtent == dynamic_extent || MyExtent == OtherExtent) &&
+            details::is_allowed_element_type_conversion<OtherElementType, element_type>::value, int> = 0>
     constexpr span(const span<OtherElementType, OtherExtent>& other) noexcept
         : storage_(other.data(), details::extent_type<OtherExtent>(other.size()))
     {}
 
+    template <
+        class OtherElementType, std::size_t OtherExtent, std::size_t MyExtent = Extent,
+        std::enable_if_t<
+            MyExtent != dynamic_extent && OtherExtent == dynamic_extent &&
+            details::is_allowed_element_type_conversion<OtherElementType, element_type>::value, int> = 0>
+    constexpr explicit span(const span<OtherElementType, OtherExtent>& other) noexcept
+        : storage_(other.data(), details::extent_type<OtherExtent>(other.size()))
+    {}
+
     ~span() noexcept = default;
     constexpr span& operator=(const span& other) noexcept = default;
 
@@ -499,7 +544,7 @@ public:
     constexpr span<element_type, Count> first() const noexcept
     {
         Expects(Count <= size());
-        return {data(), Count};
+        return span<element_type, Count>{data(), Count};
     }
 
     template <std::size_t Count>
@@ -509,7 +554,7 @@ public:
         constexpr span<element_type, Count> last() const noexcept
     {
         Expects(Count <= size());
-        return {data() + (size() - Count), Count};
+        return span<element_type, Count>{data() + (size() - Count), Count};
     }
 
     template <std::size_t Offset, std::size_t Count = dynamic_extent>
@@ -520,8 +565,8 @@ public:
         typename details::calculate_subspan_type<ElementType, Extent, Offset, Count>::type
     {
         Expects((size() >= Offset) && (Count == dynamic_extent || (Count <= size() - Offset)));
-
-        return {data() + Offset, Count == dynamic_extent ? size() - Offset : Count};
+        using type = typename details::calculate_subspan_type<ElementType, Extent, Offset, Count>::type;
+        return type{data() + Offset, Count == dynamic_extent ? size() - Offset : Count};
     }
 
     constexpr span<element_type, dynamic_extent> first(size_type count) const noexcept
@@ -582,12 +627,18 @@ public:
     constexpr iterator begin() const noexcept
     {
         const auto data = storage_.data();
+        // clang-format off
+        GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
+        // clang-format on
         return {data, data + size(), data};
     }
 
     constexpr iterator end() const noexcept
     {
         const auto data = storage_.data();
+        // clang-format off
+        GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
+        // clang-format on
         const auto endData = data + storage_.size();
         return {data, endData, endData};
     }
@@ -690,6 +741,14 @@ span(std::array<Type, Size>&)->span<Type, Size>;
 template <class Type, std::size_t Size>
 span(const std::array<Type, Size>&)->span<const Type, Size>;
 
+template <class Container,
+    class Element = std::remove_pointer_t<decltype(std::declval<Container&>().data())>>
+span(Container&)->span<Element>;
+
+template <class Container,
+    class Element = std::remove_pointer_t<decltype(std::declval<const Container&>().data())>>
+span(const Container&)->span<Element>;
+
 #endif // ( defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L) )
 
 #if defined(GSL_USE_STATIC_CONSTEXPR_WORKAROUND)
@@ -723,10 +782,12 @@ template <class ElementType, std::size_t Extent>
 span<const byte, details::calculate_byte_size<ElementType, Extent>::value>
 as_bytes(span<ElementType, Extent> s) noexcept
 {
+    using type = span<const byte, details::calculate_byte_size<ElementType, Extent>::value>;
+
     // clang-format off
     GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
     // clang-format on
-    return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
+    return type{reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
 }
 
 template <class ElementType, std::size_t Extent,
@@ -734,20 +795,17 @@ template <class ElementType, std::size_t Extent,
 span<byte, details::calculate_byte_size<ElementType, Extent>::value>
 as_writable_bytes(span<ElementType, Extent> s) noexcept
 {
+    using type = span<byte, details::calculate_byte_size<ElementType, Extent>::value>;
+
     // clang-format off
     GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
     // clang-format on
-    return {reinterpret_cast<byte*>(s.data()), s.size_bytes()};
+    return type{reinterpret_cast<byte*>(s.data()), s.size_bytes()};
 }
 
 } // namespace gsl
 
 #if defined(_MSC_VER) && !defined(__clang__)
-#if _MSC_VER < 1910
-#undef constexpr
-#pragma pop_macro("constexpr")
-
-#endif // _MSC_VER < 1910
 
 #pragma warning(pop)
 #endif // _MSC_VER

include/gsl/string_span

@@ -19,14 +19,14 @@
 
 #include <gsl/gsl_assert> // for Ensures, Expects
 #include <gsl/gsl_util>   // for narrow_cast
-#include <gsl/span_ext>       // for operator!=, operator==, dynamic_extent
+#include <gsl/span_ext>   // for operator!=, operator==, dynamic_extent
 
 #include <algorithm> // for equal, lexicographical_compare
 #include <array>     // for array
 #include <cstddef>   // for size_t, nullptr_t
 #include <cstdint>   // for PTRDIFF_MAX
 #include <cstring>
-#include <string>    // for basic_string, allocator, char_traits
+#include <string>      // for basic_string, allocator, char_traits
 #include <type_traits> // for declval, is_convertible, enable_if_t, add_...
 
 #if defined(_MSC_VER) && !defined(__clang__)
@@ -35,13 +35,13 @@
 // Turn MSVC /analyze rules that generate too much noise. TODO: fix in the tool.
 #pragma warning(disable : 26446) // TODO: bug in parser - attributes and templates
 #pragma warning(disable : 26481) // TODO: suppress does not work inside templates sometimes
+#pragma warning(disable : 4996)  // use of functions & classes marked [[deprecated]]
+#endif                           // _MSC_VER
 
-#if _MSC_VER < 1910
-#pragma push_macro("constexpr")
-#define constexpr /*constexpr*/
-
-#endif // _MSC_VER < 1910
-#endif // _MSC_VER
+#if defined(__GNUC__) || defined(__clang__)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#endif
 
 namespace gsl
 {
@@ -57,36 +57,55 @@ namespace gsl
 //
 
 template <typename CharT, std::size_t Extent = dynamic_extent>
-using basic_zstring = CharT*;
+using basic_zstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                 "information, see isocpp/CppCoreGuidelines PR#1680")]] = CharT*;
 
 template <std::size_t Extent = dynamic_extent>
-using czstring = basic_zstring<const char, Extent>;
+using czstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                            "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring<const char, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using cwzstring = basic_zstring<const wchar_t, Extent>;
+using cwzstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                             "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring<const wchar_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using cu16zstring = basic_zstring<const char16_t, Extent>;
+using cu16zstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                               "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring<const char16_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using cu32zstring = basic_zstring<const char32_t, Extent>;
+using cu32zstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                               "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring<const char32_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using zstring = basic_zstring<char, Extent>;
+using zstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                           "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring<char, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using wzstring = basic_zstring<wchar_t, Extent>;
+using wzstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                            "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring<wchar_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using u16zstring = basic_zstring<char16_t, Extent>;
+using u16zstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                              "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring<char16_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using u32zstring = basic_zstring<char32_t, Extent>;
+using u32zstring [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                              "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring<char32_t, Extent>;
 
 namespace details
 {
     template <class CharT>
-    std::size_t string_length(const CharT* str, std::size_t n)
+    [[deprecated("string_span was removed from the C++ Core Guidelines. For more information, see "
+                 "isocpp/CppCoreGuidelines PR#1680")]] constexpr std::size_t
+    string_length(const CharT* str, std::size_t n)
     {
         if (str == nullptr || n == dynamic_extent) return 0;
 
@@ -108,73 +127,87 @@ namespace details
 // Will fail-fast if sentinel cannot be found before max elements are examined.
 //
 template <typename T, const T Sentinel>
-span<T, dynamic_extent> ensure_sentinel(T* seq,
-                                        std::size_t max = static_cast<std::size_t>(-1))
+[[deprecated("string_span was removed from the C++ Core Guidelines. For more information, see "
+             "isocpp/CppCoreGuidelines PR#1680")]] constexpr span<T, dynamic_extent>
+ensure_sentinel(T* seq, std::size_t max = static_cast<std::size_t>(-1))
 {
     Ensures(seq != nullptr);
 
-    GSL_SUPPRESS(
-        f.23) // NO-FORMAT: attribute // TODO: false positive // TODO: suppress does not work
+    // clang-format off
+    GSL_SUPPRESS(f.23) // TODO: false positive // TODO: suppress does not work
+    // clang-format on
     auto cur = seq;
     Ensures(cur != nullptr); // workaround for removing the warning
 
-    GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute // TODO: suppress does not work
+    // clang-format off
+    GSL_SUPPRESS(bounds.1) // TODO: suppress does not work
+    // clang-format on
     while (static_cast<std::size_t>(cur - seq) < max && *cur != Sentinel) ++cur;
     Ensures(*cur == Sentinel);
     return {seq, static_cast<std::size_t>(cur - seq)};
 }
 
 //
-// ensure_z - creates a span for a zero terminated strings.
-// Will fail fast if a null-terminator cannot be found before
-// the limit of size_type.
+// ensure_z - creates a span for a zero terminated strings. The span will not contain the zero
+// termination. Will fail fast if a null-terminator cannot be found before the limit of size_type.
 //
 template <typename CharT>
-span<CharT, dynamic_extent> ensure_z(CharT* const& sz,
-                                     std::size_t max = static_cast<std::size_t>(-1))
+[[deprecated("string_span was removed from the C++ Core Guidelines. For more information, see "
+             "isocpp/CppCoreGuidelines PR#1680")]] constexpr span<CharT, dynamic_extent>
+ensure_z(CharT* const& sz, std::size_t max = static_cast<std::size_t>(-1))
 {
     return ensure_sentinel<CharT, CharT(0)>(sz, max);
 }
 
 template <typename CharT, std::size_t N>
-span<CharT, dynamic_extent> ensure_z(CharT (&sz)[N])
+constexpr span<CharT, dynamic_extent> ensure_z(CharT (&sz)[N])
 {
     return ensure_z(&sz[0], N);
 }
 
 template <class Cont>
-span<typename std::remove_pointer<typename Cont::pointer>::type, dynamic_extent>
+[[deprecated(
+    "string_span was removed from the C++ Core Guidelines. For more information, see "
+    "isocpp/CppCoreGuidelines PR#1680")]] constexpr span<typename std::
+                                                             remove_pointer<
+                                                                 typename Cont::pointer>::type,
+                                                         dynamic_extent>
 ensure_z(Cont& cont)
 {
     return ensure_z(cont.data(), cont.size());
 }
 
 template <typename CharT, std::size_t>
-class basic_string_span;
+class [[deprecated("string_span was removed from the C++ Core Guidelines. For more information, "
+                   "see isocpp/CppCoreGuidelines PR#1680")]] basic_string_span;
 
 namespace details
 {
     template <typename T>
-    struct is_basic_string_span_oracle : std::false_type
-    {
-    };
+    struct [
+        [deprecated("string_span was removed from the C++ Core Guidelines. For more information, "
+                    "see isocpp/CppCoreGuidelines PR#1680")]] is_basic_string_span_oracle
+        : std::false_type{};
 
     template <typename CharT, std::size_t Extent>
-    struct is_basic_string_span_oracle<basic_string_span<CharT, Extent>> : std::true_type
-    {
-    };
+    struct [[deprecated(
+        "string_span was removed from the C++ Core Guidelines. For more information, see "
+        "isocpp/CppCoreGuidelines PR#1680")]] is_basic_string_span_oracle<basic_string_span<CharT,
+                                                                                            Extent>>
+        : std::true_type{};
 
     template <typename T>
-    struct is_basic_string_span : is_basic_string_span_oracle<std::remove_cv_t<T>>
-    {
-    };
+    struct [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                        "information, see isocpp/CppCoreGuidelines PR#1680")]] is_basic_string_span
+        : is_basic_string_span_oracle<std::remove_cv_t<T>>{};
 } // namespace details
 
 //
 // string_span and relatives
 //
 template <typename CharT, std::size_t Extent = dynamic_extent>
-class basic_string_span
+class [[deprecated("string_span was removed from the C++ Core Guidelines. For more information, "
+                   "see isocpp/CppCoreGuidelines PR#1680")]] basic_string_span
 {
 public:
     using element_type = CharT;
@@ -203,11 +236,11 @@ public:
     // From static arrays - if 0-terminated, remove 0 from the view
     // All other containers allow 0s within the length, so we do not remove them
     template <std::size_t N>
-    constexpr basic_string_span(element_type (&arr)[N]) : span_(remove_z(arr))
+    constexpr basic_string_span(element_type(&arr)[N]) : span_(remove_z(arr))
     {}
 
     template <std::size_t N, class ArrayElementType = std::remove_const_t<element_type>>
-    constexpr basic_string_span(std::array<ArrayElementType, N>& arr) noexcept : span_(arr)
+    constexpr basic_string_span(std::array<ArrayElementType, N> & arr) noexcept : span_(arr)
     {}
 
     template <std::size_t N, class ArrayElementType = std::remove_const_t<element_type>>
@@ -216,8 +249,8 @@ public:
 
     // Container signature should work for basic_string after C++17 version exists
     template <class Traits, class Allocator>
-    // GSL_SUPPRESS(bounds.4) // NO-FORMAT: attribute // TODO: parser bug
-    constexpr basic_string_span(std::basic_string<element_type, Traits, Allocator>& str)
+    // GSL_SUPPRESS(bounds.4) // TODO: parser bug
+    constexpr basic_string_span(std::basic_string<element_type, Traits, Allocator> & str)
         : span_(&str[0], str.length())
     {}
 
@@ -233,7 +266,7 @@ public:
                   std::is_convertible<typename Container::pointer, pointer>::value &&
                   std::is_convertible<typename Container::pointer,
                                       decltype(std::declval<Container>().data())>::value>>
-    constexpr basic_string_span(Container& cont) : span_(cont)
+    constexpr basic_string_span(Container & cont) : span_(cont)
     {}
 
     template <class Container,
@@ -282,8 +315,8 @@ public:
         return {span_.template subspan<Offset, Count>()};
     }
 
-    constexpr basic_string_span<element_type, dynamic_extent>
-    subspan(size_type offset, size_type count = dynamic_extent) const
+    constexpr basic_string_span<element_type, dynamic_extent> subspan(
+        size_type offset, size_type count = dynamic_extent) const
     {
         return {span_.subspan(offset, count)};
     }
@@ -306,13 +339,13 @@ public:
     constexpr reverse_iterator rend() const noexcept { return span_.rend(); }
 
 private:
-    static impl_type remove_z(pointer const& sz, std::size_t max)
+    static constexpr impl_type remove_z(pointer const& sz, std::size_t max)
     {
-        return {sz, details::string_length(sz, max)};
+        return impl_type(sz, details::string_length(sz, max));
     }
 
     template <std::size_t N>
-    static impl_type remove_z(element_type (&sz)[N])
+    static constexpr impl_type remove_z(element_type(&sz)[N])
     {
         return remove_z(&sz[0], N);
     }
@@ -321,35 +354,51 @@ private:
 };
 
 template <std::size_t Extent = dynamic_extent>
-using string_span = basic_string_span<char, Extent>;
+using string_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                               "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_string_span<char, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using cstring_span = basic_string_span<const char, Extent>;
+using cstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_string_span<const char, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using wstring_span = basic_string_span<wchar_t, Extent>;
+using wstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_string_span<wchar_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using cwstring_span = basic_string_span<const wchar_t, Extent>;
+using cwstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                 "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_string_span<const wchar_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using u16string_span = basic_string_span<char16_t, Extent>;
+using u16string_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                  "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_string_span<char16_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using cu16string_span = basic_string_span<const char16_t, Extent>;
+using cu16string_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                   "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_string_span<const char16_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using u32string_span = basic_string_span<char32_t, Extent>;
+using u32string_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                  "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_string_span<char32_t, Extent>;
 
 template <std::size_t Extent = dynamic_extent>
-using cu32string_span = basic_string_span<const char32_t, Extent>;
+using cu32string_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                   "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_string_span<const char32_t, Extent>;
 
 //
 // to_string() allow (explicit) conversions from string_span to string
 //
 
 template <typename CharT, std::size_t Extent>
-std::basic_string<typename std::remove_const<CharT>::type>
+constexpr std::basic_string<typename std::remove_const<CharT>::type>
 to_string(basic_string_span<CharT, Extent> view)
 {
     return {view.data(), narrow_cast<std::size_t>(view.length())};
@@ -357,32 +406,38 @@ to_string(basic_string_span<CharT, Extent> view)
 
 template <typename CharT, typename Traits = typename std::char_traits<CharT>,
           typename Allocator = std::allocator<CharT>, typename gCharT, std::size_t Extent>
-std::basic_string<CharT, Traits, Allocator> to_basic_string(basic_string_span<gCharT, Extent> view)
+constexpr std::basic_string<CharT, Traits, Allocator>
+to_basic_string(basic_string_span<gCharT, Extent> view)
 {
     return {view.data(), narrow_cast<std::size_t>(view.length())};
 }
 
 template <class ElementType, std::size_t Extent>
-basic_string_span<const byte, details::calculate_byte_size<ElementType, Extent>::value>
+constexpr basic_string_span<const byte, details::calculate_byte_size<ElementType, Extent>::value>
 as_bytes(basic_string_span<ElementType, Extent> s) noexcept
 {
-    GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+    // clang-format off
+    GSL_SUPPRESS(type.1)
+    // clang-format on
     return {reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
 }
 
 template <class ElementType, std::size_t Extent,
           class = std::enable_if_t<!std::is_const<ElementType>::value>>
-basic_string_span<byte, details::calculate_byte_size<ElementType, Extent>::value>
+constexpr basic_string_span<byte, details::calculate_byte_size<ElementType, Extent>::value>
 as_writable_bytes(basic_string_span<ElementType, Extent> s) noexcept
 {
-    GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
+    // clang-format off
+    GSL_SUPPRESS(type.1)
+    // clang-format on
     return {reinterpret_cast<byte*>(s.data()), s.size_bytes()};
 }
 
 // zero-terminated string span, used to convert
 // zero-terminated spans to legacy strings
 template <typename CharT, std::size_t Extent = dynamic_extent>
-class basic_zstring_span
+class [[deprecated("string_span was removed from the C++ Core Guidelines. For more information, "
+                   "see isocpp/CppCoreGuidelines PR#1680")]] basic_zstring_span
 {
 public:
     using value_type = CharT;
@@ -400,14 +455,15 @@ public:
     constexpr basic_zstring_span(impl_type s) : span_(s)
     {
         // expects a zero-terminated span
-        Expects(s[s.size() - 1] == '\0');
+        Expects(s.size() > 0);
+        Expects(s[s.size() - 1] == value_type{});
     }
 
     // copy
     constexpr basic_zstring_span(const basic_zstring_span& other) = default;
 
     // move
-    constexpr basic_zstring_span(basic_zstring_span&& other) = default;
+    constexpr basic_zstring_span(basic_zstring_span && other) = default;
 
     // assign
     constexpr basic_zstring_span& operator=(const basic_zstring_span& other) = default;
@@ -415,12 +471,11 @@ public:
     // move assign
     constexpr basic_zstring_span& operator=(basic_zstring_span&& other) = default;
 
-    constexpr bool empty() const noexcept { return span_.size() == 0; }
+    constexpr bool empty() const noexcept { return false; }
 
     constexpr string_span_type as_string_span() const noexcept
     {
-        const auto sz = span_.size();
-        return {span_.data(), sz > 1 ? sz - 1 : 0};
+        return {span_.data(), span_.size() - 1};
     }
     constexpr string_span_type ensure_z() const { return gsl::ensure_z(span_); }
 
@@ -431,28 +486,44 @@ private:
 };
 
 template <std::size_t Max = dynamic_extent>
-using zstring_span = basic_zstring_span<char, Max>;
+using zstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring_span<char, Max>;
 
 template <std::size_t Max = dynamic_extent>
-using wzstring_span = basic_zstring_span<wchar_t, Max>;
+using wzstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                 "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring_span<wchar_t, Max>;
 
 template <std::size_t Max = dynamic_extent>
-using u16zstring_span = basic_zstring_span<char16_t, Max>;
+using u16zstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                   "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring_span<char16_t, Max>;
 
 template <std::size_t Max = dynamic_extent>
-using u32zstring_span = basic_zstring_span<char32_t, Max>;
+using u32zstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                   "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring_span<char32_t, Max>;
 
 template <std::size_t Max = dynamic_extent>
-using czstring_span = basic_zstring_span<const char, Max>;
+using czstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                 "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring_span<const char, Max>;
 
 template <std::size_t Max = dynamic_extent>
-using cwzstring_span = basic_zstring_span<const wchar_t, Max>;
+using cwzstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For more "
+                                  "information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring_span<const wchar_t, Max>;
 
 template <std::size_t Max = dynamic_extent>
-using cu16zstring_span = basic_zstring_span<const char16_t, Max>;
+using cu16zstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For "
+                                    "more information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring_span<const char16_t, Max>;
 
 template <std::size_t Max = dynamic_extent>
-using cu32zstring_span = basic_zstring_span<const char32_t, Max>;
+using cu32zstring_span [[deprecated("string_span was removed from the C++ Core Guidelines. For "
+                                    "more information, see isocpp/CppCoreGuidelines PR#1680")]] =
+    basic_zstring_span<const char32_t, Max>;
 
 // operator ==
 template <class CharT, std::size_t Extent, class T,
@@ -476,7 +547,7 @@ bool operator==(const T& one, const gsl::basic_string_span<CharT, Extent>& other
 }
 
 // operator !=
-template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator!=(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -485,7 +556,7 @@ bool operator!=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -495,7 +566,7 @@ bool operator!=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 }
 
 // operator<
-template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator<(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -505,7 +576,7 @@ bool operator<(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -521,7 +592,7 @@ bool operator<(const T& one, gsl::basic_string_span<CharT, Extent> other)
 // so the cases below are already covered by the previous operators
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -535,7 +606,7 @@ bool operator<(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -550,7 +621,7 @@ bool operator<(const T& one, gsl::basic_string_span<CharT, Extent> other)
 #endif
 
 // operator <=
-template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator<=(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -559,7 +630,7 @@ bool operator<=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -574,7 +645,7 @@ bool operator<=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 // so the cases below are already covered by the previous operators
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -587,7 +658,7 @@ bool operator<=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -601,7 +672,7 @@ bool operator<=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 #endif
 
 // operator>
-template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator>(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -610,7 +681,7 @@ bool operator>(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -625,7 +696,7 @@ bool operator>(const T& one, gsl::basic_string_span<CharT, Extent> other)
 // so the cases below are already covered by the previous operators
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -638,7 +709,7 @@ bool operator>(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -652,7 +723,7 @@ bool operator>(const T& one, gsl::basic_string_span<CharT, Extent> other)
 #endif
 
 // operator >=
-template <typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+template <typename CharT, std::size_t Extent = dynamic_extent, typename T,
           typename = std::enable_if_t<std::is_convertible<
               T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value>>
 bool operator>=(gsl::basic_string_span<CharT, Extent> one, const T& other)
@@ -661,7 +732,7 @@ bool operator>=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename = std::enable_if_t<
         std::is_convertible<T, gsl::basic_string_span<std::add_const_t<CharT>, Extent>>::value &&
         !gsl::details::is_basic_string_span<T>::value>>
@@ -676,7 +747,7 @@ bool operator>=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 // so the cases below are already covered by the previous operators
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -689,7 +760,7 @@ bool operator>=(gsl::basic_string_span<CharT, Extent> one, const T& other)
 }
 
 template <
-    typename CharT, std::size_t Extent = gsl::dynamic_extent, typename T,
+    typename CharT, std::size_t Extent = dynamic_extent, typename T,
     typename DataType = typename T::value_type,
     typename = std::enable_if_t<
         !gsl::details::is_span<T>::value && !gsl::details::is_basic_string_span<T>::value &&
@@ -706,11 +777,9 @@ bool operator>=(const T& one, gsl::basic_string_span<CharT, Extent> other)
 #if defined(_MSC_VER) && !defined(__clang__)
 #pragma warning(pop)
 
-#if _MSC_VER < 1910
-#undef constexpr
-#pragma pop_macro("constexpr")
-
-#endif // _MSC_VER < 1910
 #endif // _MSC_VER
 
+#if defined(__GNUC__) || defined(__clang__)
+#pragma GCC diagnostic pop
+#endif
 #endif // GSL_STRING_SPAN_H

library.json

@@ -0,0 +1,11 @@
+{
+    "name": "GSL",
+    "version": "1.0.0",
+    "build": {
+        "includeDir": "include",
+        "srcFilter":
+        [
+            ".<*>"
+        ]
+    }
+}

tests/CMakeLists.txt

@@ -1,37 +1,42 @@
 cmake_minimum_required(VERSION 3.0.2)
 
 project(GSLTests CXX)
+include(FindPkgConfig)
 
 # will make visual studio generated project group files
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 
-configure_file(CMakeLists.txt.in googletest-download/CMakeLists.txt)
-execute_process(
-    COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
-    RESULT_VARIABLE result
-    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download
-)
-if(result)
-    message(FATAL_ERROR "CMake step for googletest failed: ${result}")
+pkg_search_module(GTestMain gtest_main)
+if (NOT GTestMain_FOUND)
+    configure_file(CMakeLists.txt.in googletest-download/CMakeLists.txt)
+    execute_process(
+        COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
+        RESULT_VARIABLE result
+        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download
+    )
+    if(result)
+        message(FATAL_ERROR "CMake step for googletest failed: ${result}")
+    endif()
+
+    execute_process(
+        COMMAND ${CMAKE_COMMAND} --build .
+        RESULT_VARIABLE result
+        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download
+    )
+    if(result)
+        message(FATAL_ERROR "CMake step for googletest failed: ${result}")
+    endif()
+
+    set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+    set(GTestMain_LIBRARIES gtest_main)
+
+    add_subdirectory(
+        ${CMAKE_CURRENT_BINARY_DIR}/googletest-src
+        ${CMAKE_CURRENT_BINARY_DIR}/googletest-build
+        EXCLUDE_FROM_ALL
+    )
 endif()
 
-execute_process(
-    COMMAND ${CMAKE_COMMAND} --build .
-    RESULT_VARIABLE result
-    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download
-)
-if(result)
-    message(FATAL_ERROR "CMake step for googletest failed: ${result}")
-endif()
-
-set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
-
-add_subdirectory(
-    ${CMAKE_CURRENT_BINARY_DIR}/googletest-src
-    ${CMAKE_CURRENT_BINARY_DIR}/googletest-build
-    EXCLUDE_FROM_ALL
-)
-
 if (MSVC AND (GSL_CXX_STANDARD EQUAL 17))
     set(GSL_CPLUSPLUS_OPT -Zc:__cplusplus -permissive-)
 endif()
@@ -149,7 +154,7 @@ function(add_gsl_test name)
     target_link_libraries(${name}
         GSL
         gsl_tests_config
-        gtest_main
+        ${GTestMain_LIBRARIES}
     )
     add_test(
         ${name}
@@ -254,7 +259,7 @@ function(add_gsl_test_noexcept name)
     target_link_libraries(${name}
         GSL
         gsl_tests_config_noexcept
-        gtest_main
+        ${GTestMain_LIBRARIES}
     )
     add_test(
       ${name}
@@ -264,5 +269,4 @@ function(add_gsl_test_noexcept name)
     set_property(TARGET ${name} PROPERTY FOLDER "GSL_tests_noexcept")
 endfunction()
 
-add_gsl_test_noexcept(no_exception_throw_tests)
 add_gsl_test_noexcept(no_exception_ensure_tests)

tests/no_exception_throw_tests.cpp

@@ -1,48 +0,0 @@
-///////////////////////////////////////////////////////////////////////////////
-//
-// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
-//
-// This code is licensed under the MIT License (MIT).
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
-//
-///////////////////////////////////////////////////////////////////////////////
-
-#include <cstdlib>        // for std::exit
-#include <gsl/gsl_assert> // for get_terminate
-#include <gsl/gsl_util>   // for narrow
-
-int narrow_no_throw()
-{
-    const long long bigNumber = 0x0fffffffffffffff;
-    return gsl::narrow<int>(bigNumber);
-}
-
-[[noreturn]] void test_terminate() { std::exit(0); }
-
-void setup_termination_handler() noexcept
-{
-#if defined(GSL_MSVC_USE_STL_NOEXCEPTION_WORKAROUND)
-
-    auto& handler = gsl::details::get_terminate_handler();
-    handler = &test_terminate;
-
-#else
-
-    std::set_terminate(test_terminate);
-
-#endif
-}
-
-int main()
-{
-    setup_termination_handler();
-    narrow_no_throw();
-    return -1;
-}

tests/span_compatibility_tests.cpp

@@ -846,8 +846,6 @@ static_assert(!std::is_constructible<gsl::span<int, 3>, std::array<int, 500>&>::
               "!std::is_constructible<gsl::span<int, 3>, std::array<int, 500>&>");
 static_assert(!std::is_constructible<gsl::span<int, 3>, const std::array<int, 3>&>::value,
               "!std::is_constructible<gsl::span<int, 3>, const std::array<int, 3>&>");
-static_assert(!std::is_constructible<gsl::span<int, 3>, const gsl::span<int>&>::value,
-              "!std::is_constructible<gsl::span<int, 3>, const gsl::span<int>&>");
 static_assert(!std::is_constructible<gsl::span<int, 3>, const gsl::span<int, 500>&>::value,
               "!std::is_constructible<gsl::span<int, 3>, const gsl::span<int, 500>&>");
 static_assert(!std::is_constructible<gsl::span<int, 3>, const gsl::span<const int>&>::value,
@@ -866,12 +864,8 @@ static_assert(!std::is_constructible<gsl::span<const int>, std::array<double, 3>
 static_assert(!std::is_constructible<gsl::span<const int>, const gsl::span<double, 3>&>::value,
               "!std::is_constructible<gsl::span<const int>, const gsl::span<double, 3>&>");
 
-static_assert(!std::is_constructible<gsl::span<const int, 3>, const gsl::span<int>&>::value,
-              "!std::is_constructible<gsl::span<const int, 3>, const gsl::span<int>&>");
 static_assert(!std::is_constructible<gsl::span<const int, 3>, const gsl::span<int, 500>&>::value,
               "!std::is_constructible<gsl::span<const int, 3>, const gsl::span<int, 500>&>");
-static_assert(!std::is_constructible<gsl::span<const int, 3>, const gsl::span<const int>&>::value,
-              "!std::is_constructible<gsl::span<const int, 3>, const gsl::span<const int>&>");
 static_assert(
     !std::is_constructible<gsl::span<const int, 3>, const gsl::span<const int, 500>&>::value,
     "!std::is_constructible<gsl::span<const int, 3>, const gsl::span<const int, 500>&>");
@@ -925,6 +919,14 @@ static_assert(!std::is_constructible<gsl::span<const Derived>, std::array<Base,
 static_assert(!std::is_constructible<gsl::span<const Derived>, const std::array<Base, 3>&>::value,
               "!std::is_constructible<gsl::span<const Derived>, const std::array<Base, 3>&>");
 
+// Explicit construction enabled in P1976R2
+static_assert(std::is_constructible<gsl::span<int, 3>, const gsl::span<int>&>::value,
+              "std::is_constructible<gsl::span<int, 3>, const gsl::span<int>&>");
+static_assert(std::is_constructible<gsl::span<const int, 3>, const gsl::span<int>&>::value,
+              "std::is_constructible<gsl::span<const int, 3>, const gsl::span<int>&>");
+static_assert(std::is_constructible<gsl::span<const int, 3>, const gsl::span<const int>&>::value,
+              "std::is_constructible<gsl::span<const int, 3>, const gsl::span<const int>&>");
+
 // no throw copy constructor
 static_assert(std::is_nothrow_copy_constructible<gsl::span<int>>::value,
               "std::is_nothrow_copy_constructible<gsl::span<int>>");

tests/span_tests.cpp

@@ -31,6 +31,16 @@
 #include <vector>      // for vector
 #include <utility>
 
+// the string_view include and macro are used in the deduction guide verification
+#if (defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L))
+#ifdef __has_include
+#if __has_include(<string_view>)
+#include <string_view>
+#define HAS_STRING_VIEW
+#endif // __has_include(<string_view>)
+#endif // __has_include
+#endif // (defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L))
+
 using namespace std;
 using namespace gsl;
 
@@ -1144,7 +1154,7 @@ TEST(span_test, from_array_constructor)
 
      // you can convert statically
      {
-         const span<int, 2> s2 = {&arr[0], 2};
+         const span<int, 2> s2{&arr[0], 2};
          static_cast<void>(s2);
      }
      {
@@ -1180,7 +1190,7 @@ TEST(span_test, from_array_constructor)
  #endif
      {
          auto f = [&]() {
-             const span<int, 4> _s4 = {arr2, 2};
+             const span<int, 4> _s4{arr2, 2};
              static_cast<void>(_s4);
          };
          EXPECT_DEATH(f(), deathstring);
@@ -1227,6 +1237,30 @@ TEST(span_test, from_array_constructor)
      EXPECT_FALSE((std::is_default_constructible<span<int, 42>>::value));
  }
 
+ TEST(span_test, std_container_ctad)
+ {
+#if (defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L))
+    // this test is just to verify that these compile
+    {
+        std::vector<int> v{1,2,3,4};
+        gsl::span sp{v};
+        static_assert(std::is_same<decltype(sp), gsl::span<int>>::value);
+    }
+    {
+        std::string str{"foo"};
+        gsl::span sp{str};
+        static_assert(std::is_same<decltype(sp), gsl::span<char>>::value);
+    }
+#ifdef HAS_STRING_VIEW
+    {
+        std::string_view sv{"foo"};
+        gsl::span sp{sv};
+        static_assert(std::is_same<decltype(sp), gsl::span<const char>>::value);
+    }
+#endif
+#endif
+ }
+
  TEST(span_test, front_back)
  {
     int arr[5] = {1,2,3,4,5};

tests/utils_tests.cpp

@@ -16,8 +16,8 @@
 
 #include <gtest/gtest.h>
 
-#include <gsl/gsl_util> // for narrow, finally, narrow_cast, narrowing_e...
-
+#include <gsl/gsl_util>     // finally, narrow_cast
+#include <gsl/gsl_narrow>   // for narrow, narrowing_error
 #include <algorithm>   // for move
 #include <functional>  // for reference_wrapper, _Bind_helper<>::type
 #include <limits>      // for numeric_limits
@@ -29,7 +29,6 @@ using namespace gsl;
 
 namespace
 {
-static constexpr char deathstring[] = "Expected Death";
 void f(int& i) { i += 1; }
 static int j = 0;
 void g() { j += 1; }
@@ -71,6 +70,28 @@ TEST(utils_tests, finally_lambda_move)
     EXPECT_TRUE(i == 1);
 }
 
+TEST(utils_tests, finally_const_lvalue_lambda)
+{
+    int i = 0;
+    {
+        const auto const_lvalue_lambda = [&]() { f(i); };
+        auto _ = finally(const_lvalue_lambda);
+        EXPECT_TRUE(i == 0);
+    }
+    EXPECT_TRUE(i == 1);
+}
+
+TEST(utils_tests, finally_mutable_lvalue_lambda)
+{
+    int i = 0;
+    {
+        auto mutable_lvalue_lambda = [&]() { f(i); };
+        auto _ = finally(mutable_lvalue_lambda);
+        EXPECT_TRUE(i == 0);
+    }
+    EXPECT_TRUE(i == 1);
+}
+
 TEST(utils_tests, finally_function_with_bind)
 {
     int i = 0;
@@ -104,17 +125,12 @@ TEST(utils_tests, narrow_cast)
 
 TEST(utils_tests, narrow)
 {
-    std::set_terminate([] {
-        std::cerr << "Expected Death. narrow";
-        std::abort();
-    });
-
     int n = 120;
     const char c = narrow<char>(n);
     EXPECT_TRUE(c == 120);
 
     n = 300;
-    EXPECT_DEATH(narrow<char>(n), deathstring);
+    EXPECT_THROW(narrow<char>(n), narrowing_error);
 
     const auto int32_max = std::numeric_limits<int32_t>::max();
     const auto int32_min = std::numeric_limits<int32_t>::min();
@@ -123,14 +139,9 @@ TEST(utils_tests, narrow)
     EXPECT_TRUE(narrow<uint32_t>(int32_t(1)) == 1);
     EXPECT_TRUE(narrow<uint32_t>(int32_max) == static_cast<uint32_t>(int32_max));
 
-    EXPECT_DEATH(narrow<uint32_t>(int32_t(-1)), deathstring);
-    EXPECT_DEATH(narrow<uint32_t>(int32_min), deathstring);
+    EXPECT_THROW(narrow<uint32_t>(int32_t(-1)), narrowing_error);
+    EXPECT_THROW(narrow<uint32_t>(int32_min), narrowing_error);
 
     n = -42;
-    EXPECT_DEATH(narrow<unsigned>(n), deathstring);
-
-#if GSL_CONSTEXPR_NARROW
-    static_assert(narrow<char>(120) == 120, "Fix GSL_CONSTEXPR_NARROW");
-#endif
-
+    EXPECT_THROW(narrow<unsigned>(n), narrowing_error);
 }