Merge pull request #892 from JordanMaples/dev/jomaples/gsl3.1.0

Update project version to GSL 3.1.0

.github/workflows/main.yml

@@ -0,0 +1,94 @@
+name: CI
+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
+
+  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 {} \\\;

.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")
@@ -89,15 +89,31 @@ 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)
+write_basic_package_version_file(
+    ${CMAKE_CURRENT_BINARY_DIR}/Microsoft.GSLConfigVersion.cmake
+    COMPATIBILITY SameMajorVersion
+)
+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

@@ -1,4 +1,5 @@
-# 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).
@@ -21,34 +22,33 @@ This project has adopted the [Microsoft Open Source Code of Conduct](https://ope
 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.
 
 # 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](https://github.com/microsoft/GSL/workflows/CI/badge.svg)
+Android | ![CI](https://github.com/microsoft/GSL/workflows/CI/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:

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_util

@@ -30,18 +30,8 @@
 #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
-#else
-#define GSL_CONSTEXPR_NARROW 1
-#endif
-
 namespace gsl
 {
 //
@@ -96,6 +86,10 @@ constexpr T narrow_cast(U&& u) noexcept
     return static_cast<T>(std::forward<U>(u));
 }
 
+struct narrowing_error : public std::exception
+{
+};
+
 namespace details
 {
     template <class T, class U>
@@ -109,15 +103,13 @@ namespace details
 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 (static_cast<U>(t) != u) throw narrowing_error{};
     if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{})))
-        gsl::details::terminate();
+        throw narrowing_error{};
     return t;
 }
 
@@ -154,11 +146,6 @@ 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
@@ -62,7 +62,7 @@
 #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 +392,9 @@ 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 +462,7 @@ 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);
         }
 

include/gsl/span

@@ -19,7 +19,6 @@
 
 #include <gsl/gsl_assert> // for Expects
 #include <gsl/gsl_byte>   // for byte
-#include <gsl/gsl_util>   // for narrow_cast, narrow
 
 #include <array>       // for array
 #include <cstddef>     // for ptrdiff_t, size_t, nullptr_t
@@ -39,12 +38,6 @@
 #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
@@ -344,17 +337,18 @@ 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 +358,10 @@ 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 +372,12 @@ 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 +421,28 @@ 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 != gsl::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
+    template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent == gsl::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 != gsl::dynamic_extent, int> = 0>
+    constexpr explicit span(pointer firstElem, pointer lastElem) noexcept
         : storage_(firstElem, static_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 == gsl::dynamic_extent, int> = 0>
+    constexpr span(pointer firstElem, pointer lastElem) noexcept
+        : storage_(firstElem, static_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 +467,74 @@ 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 +543,7 @@ 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 +553,7 @@ 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 +564,8 @@ 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 +626,18 @@ 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 +740,14 @@ 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 +781,12 @@ 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 +794,17 @@ 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

@@ -36,11 +36,6 @@
 #pragma warning(disable : 26446) // TODO: bug in parser - attributes and templates
 #pragma warning(disable : 26481) // TODO: suppress does not work inside templates sometimes
 
-#if _MSC_VER < 1910
-#pragma push_macro("constexpr")
-#define constexpr /*constexpr*/
-
-#endif // _MSC_VER < 1910
 #endif // _MSC_VER
 
 namespace gsl
@@ -308,7 +303,7 @@ public:
 private:
     static 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>
@@ -706,11 +701,6 @@ 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
 
 #endif // GSL_STRING_SPAN_H

tests/CMakeLists.txt

@@ -264,5 +264,4 @@ 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

@@ -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; }
@@ -104,17 +103,12 @@ 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 +117,9 @@ 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);
 }