Merge branch 'microsoft:main' into gh-1129

fixes: https://github.com/microsoft/GSL/issues/1162

gcc has a bug that generates a call to the copy constructor when list
initializing a const reference. This PR offers a workaround which is to
direct initialize the value.

see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117900

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,29 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: 'Status: Open, Type: Bug'
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+```c++
+#include <gsl>
+
+// your repro here: ...
+```
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Spec (please complete the following information):**
+ - OS: [e.g. Windows]
+ - Compiler: [e.g. MSVC]
+ - C++ Version: [e.g. C++20]
+
+**Additional context**
+Add any other context about the problem here.

.github/workflows/android.yml

@@ -38,7 +38,7 @@ jobs:
           echo "Emulator starting in background"
 
       - name: Configure
-        run: cmake -Werror=dev -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_LATEST_HOME/build/cmake/android.toolchain.cmake -DANDROID_PLATFORM=16 -DANDROID_ABI=x86_64 -DCMAKE_BUILD_TYPE=Debug ..
+        run: cmake -DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_LATEST_HOME/build/cmake/android.toolchain.cmake -DANDROID_PLATFORM=16 -DANDROID_ABI=x86_64 -DCMAKE_BUILD_TYPE=Debug ..
 
       - name: Build
         run: cmake --build . --parallel

.github/workflows/compilers.yml

@@ -23,6 +23,13 @@ jobs:
         exclude:
           - gcc_version: 10
             cxx_version: 23
+          # https://github.com/google/googletest/issues/4232
+          # Looks like GoogleTest is not interested in making version 1.14
+          # work with gcc-12.
+          - gcc_version: 12
+            cxx_version: 20
+          - gcc_version: 12
+            cxx_version: 23
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -54,7 +61,7 @@ jobs:
   xcode:
     strategy:
       matrix:
-        xcode_version: [ '14.3.1', '15.4' ]
+        xcode_version: [ '15.4' ]
         build_type: [ Debug, Release ]
         cxx_version: [ 14, 17, 20, 23 ]
     runs-on: macos-latest

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.14...3.16)
 
-project(GSL VERSION 4.0.0 LANGUAGES CXX)
+project(GSL VERSION 4.1.0 LANGUAGES CXX)
 
 add_library(GSL INTERFACE)
 add_library(Microsoft.GSL::GSL ALIAS GSL)

README.md

@@ -1,5 +1,6 @@
 # GSL: Guidelines Support Library
-[![Build Status](https://dev.azure.com/cppstat/GSL/_apis/build/status/microsoft.GSL?branchName=main)](https://dev.azure.com/cppstat/GSL/_build/latest?definitionId=1&branchName=main)
+[![CI](https://github.com/Microsoft/GSL/actions/workflows/compilers.yml/badge.svg)](https://github.com/microsoft/GSL/actions/workflows/compilers.yml?query=branch%3Amain)
+[![vcpkg](https://img.shields.io/vcpkg/v/ms-gsl)](https://vcpkg.io/en/package/ms-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).
@@ -106,8 +107,8 @@ If you successfully port GSL to another platform, we would love to hear from you
 
 Target | CI/CD Status
 :------- | -----------:
-iOS | ![CI_iOS](https://github.com/microsoft/GSL/workflows/CI_iOS/badge.svg)
+iOS | [![CI_iOS](https://github.com/microsoft/GSL/workflows/CI_iOS/badge.svg?branch=main)](https://github.com/microsoft/GSL/actions/workflows/ios.yml?query=branch%3Amain)
-Android | ![CI_Android](https://github.com/microsoft/GSL/workflows/CI_Android/badge.svg)
+Android | [![CI_Android](https://github.com/microsoft/GSL/workflows/CI_Android/badge.svg?branch=main)](https://github.com/microsoft/GSL/actions/workflows/android.yml?query=branch%3Amain)
 
 Note: These CI/CD steps are run with each pull request, however failures in them are non-blocking.
 
@@ -197,7 +198,7 @@ include(FetchContent)
 
 FetchContent_Declare(GSL
     GIT_REPOSITORY "https://github.com/microsoft/GSL"
-    GIT_TAG "v4.0.0"
+    GIT_TAG "v4.1.0"
     GIT_SHALLOW ON
 )
 

include/gsl/pointers

@@ -75,7 +75,7 @@ using std::unique_ptr;
 // T must be a pointer type
 // - disallow construction from any type other than pointer type
 //
-template <class T, class = std::enable_if_t<std::is_pointer<T>::value>>
+template <class T, std::enable_if_t<std::is_pointer<T>::value, bool> = true>
 using owner = T;
 
 //
@@ -117,7 +117,7 @@ public:
     not_null(const not_null& other) = default;
     not_null& operator=(const not_null& other) = default;
     constexpr details::value_or_reference_return_t<T> get() const
-        noexcept(noexcept(details::value_or_reference_return_t<T>{std::declval<T&>()}))
+        noexcept(noexcept(details::value_or_reference_return_t<T>(std::declval<T&>())))
     {
         return ptr_;
     }

include/gsl/span

@@ -140,7 +140,9 @@ namespace details
 
         constexpr span_iterator(pointer begin, pointer end, pointer current)
             : begin_(begin), end_(end), current_(current)
-        {}
+        {
+            Expects(begin_ <= current_ && current <= end_);
+        }
 
         constexpr operator span_iterator<const Type>() const noexcept
         {
@@ -149,21 +151,18 @@ namespace details
 
         constexpr reference operator*() const noexcept
         {
-            Expects(begin_ && end_);
+            Expects(current_ != end_);
-            Expects(begin_ <= current_ && current_ < end_);
             return *current_;
         }
 
         constexpr pointer operator->() const noexcept
         {
-            Expects(begin_ && end_);
+            Expects(current_ != end_);
-            Expects(begin_ <= current_ && current_ < end_);
             return current_;
         }
         constexpr span_iterator& operator++() noexcept
         {
-            Expects(begin_ && current_ && end_);
+            Expects(current_ != end_);
-            Expects(current_ < end_);
             // clang-format off
             GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
             // clang-format on
@@ -180,8 +179,7 @@ namespace details
 
         constexpr span_iterator& operator--() noexcept
         {
-            Expects(begin_ && end_);
+            Expects(begin_ != current_);
-            Expects(begin_ < current_);
             --current_;
             return *this;
         }

tests/CMakeLists.txt

@@ -110,6 +110,7 @@ if(MSVC) # MSVC or simulating MSVC
           -Wno-shift-sign-overflow # GTest gtest-port.h
           -Wno-undef # GTest
           -Wno-used-but-marked-unused # GTest EXPECT_DEATH
+          -Wno-switch-default # GTest EXPECT_DEATH
           $<$<EQUAL:${GSL_CXX_STANDARD},14>: # no support for [[maybe_unused]]
             -Wno-unused-member-function
             -Wno-unused-variable

tests/CMakeLists.txt.in

@@ -1,10 +1,10 @@
-cmake_minimum_required(VERSION 3.0.2)
+cmake_minimum_required(VERSION 3.13)
 project(googletest-download NONE)
 
 include(ExternalProject)
 ExternalProject_Add(googletest
   GIT_REPOSITORY    https://github.com/google/googletest.git
-  GIT_TAG           1b18723e874b256c1e39378c6774a90701d70f7a
+  GIT_TAG           v1.14.0
   SOURCE_DIR        "${CMAKE_CURRENT_BINARY_DIR}/googletest-src"
   BINARY_DIR        "${CMAKE_CURRENT_BINARY_DIR}/googletest-build"
   CONFIGURE_COMMAND ""