Fix/implement C++2020 compilation, tests, and CI (#1017)

* Fix C++20 bugs and tests
* Rework CI for C++2020 tests
* Update readme compiler versions

README.md

@@ -86,16 +86,14 @@ This is based on [CppCoreGuidelines semi-specification](https://github.com/isocp
 
 # Quick Start
 ## Supported Compilers
-The GSL officially supports the current and previous major release of MSVC, GCC, Clang, and XCode's Apple-Clang.
+The GSL officially supports the following versions of MSVC, GCC, Clang, and XCode's Apple-Clang.
-See our latest test results for the most up-to-date list of supported configurations.
 
 Compiler |Toolset Versions Currently Tested
 :------- |--:
- XCode |11.4 & 10.3
+ XCode | 12.4 & 11.3
- GCC |9 & 8
+ GCC | 9.3.0 & 7.5.0
- Clang |11 &  10
+ Clang | 11.0.0 & 9.0.0
- Visual Studio with MSVC | VS2017 (15.9) & VS2019 (16.4) 
+ Visual Studio with MSVC | VS2017 (15.9.21) & VS2019 (16.11.2)
- Visual Studio with LLVM | VS2017 (Clang 9) & VS2019 (Clang 10)
 
 ---
 If you successfully port GSL to another platform, we would love to hear from you!

azure-pipelines.yml

@@ -18,10 +18,12 @@ stages:
     parameters:
       jobName: 'Validate GCC latest'
       imageName: ubuntu-20.04
+      CXXVersions: [ 14, 17 ]
   - template: ./pipelines/jobs.yml
     parameters:
       jobName: 'Validate GCC Previous'
       imageName: ubuntu-18.04
+      CXXVersions: [ 14, 17 ]
 
 # Clang
 - stage: Clang
@@ -40,6 +42,7 @@ stages:
     parameters:
       jobName: 'Validate Clang Previous'
       imageName: ubuntu-18.04
+      CXXVersions: [ 14, 17 ]
 
 # MSVC
 - stage: MSVC
@@ -53,6 +56,7 @@ stages:
     parameters:
       jobName: 'Validate MSVC Previous'
       imageName: vs2017-win2016
+      CXXVersions: [ 14, 17 ]
 
 # Apple-Clang
 - stage: Apple_Clang
@@ -62,7 +66,9 @@ stages:
     parameters:
       jobName: 'Validate Apple-Clang latest'
       imageName: macos-10.15
+      CXXVersions: [ 14, 17 ]
   - template: ./pipelines/jobs.yml
     parameters:
       jobName: 'Validate Apple-Clang Previous'
       imageName: macos-10.14
+      CXXVersions: [ 14, 17 ]

include/gsl/util

@@ -143,10 +143,10 @@ GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
 
 #if defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
 template <class T, size_t extent = std::dynamic_extent>
-constexpr auto at(std::span<T, extent> sp, const index i)
+constexpr auto at(std::span<T, extent> sp, const index i) -> decltype(sp[sp.size()])
 {
-    Expects(i >= 0 && i < narrow_cast<i>(sp.size()));
+    Expects(i >= 0 && i < narrow_cast<index>(sp.size()));
-    return sp[i];
+    return sp[gsl::narrow_cast<size_t>(i)];
 }
 #endif // __cpp_lib_span >= 202002L
 } // namespace gsl

pipelines/jobs.yml

@@ -1,26 +1,19 @@
 parameters:
   jobName: ''
   imageName: ''
+  CXXVersions: [ 14, 17, 20 ]
+  buildTypes: [ 'Debug', 'Release' ]
 
 jobs:
-- job:
+- ${{ each CXXVersion in parameters.CXXVersions }}:
-  displayName: ${{ parameters.imageName }}
+  - ${{ each buildType in parameters.buildTypes }}:
-  pool:
+    - job:
-    vmImage: ${{ parameters.imageName }}
+      displayName: ${{ format('{0} {1} C++{2}', parameters.imageName, buildType, CXXVersion) }}
-  strategy:
+      pool:
-    matrix:
+        vmImage: ${{ parameters.imageName }}
-      14_debug:
+      continueOnError: false
-        GSL_CXX_STANDARD: '14'
+      steps:
-        BUILD_TYPE: 'Debug'
+      - template: ./steps.yml
-      14_release:
+        parameters:
-        GSL_CXX_STANDARD: '14'
+          buildType: ${{ buildType }}
-        BUILD_TYPE: 'Release'
+          CXXVersion: ${{ CXXVersion }}
-      17_debug:
-        GSL_CXX_STANDARD: '17'
-        BUILD_TYPE: 'Debug'
-      17_release:
-        GSL_CXX_STANDARD: '17'
-        BUILD_TYPE: 'Release'
-  continueOnError: false
-  steps:
-  - template: ./steps.yml

pipelines/steps.yml

@@ -1,9 +1,13 @@
+parameters:
+    buildType: ''
+    CXXVersion: ''
+
 steps:
   - task: CMake@1
     name: Configure
     inputs:
       workingDirectory: build
-      cmakeArgs: '-DCMAKE_CXX_STANDARD=$(GSL_CXX_STANDARD) -DCMAKE_BUILD_TYPE=$(BUILD_TYPE) -Werror=dev .. '
+      cmakeArgs: '-DGSL_CXX_STANDARD=${{ parameters.CXXVersion }} -DCMAKE_BUILD_TYPE=${{ parameters.buildType }} -DCI_TESTING:BOOL=ON -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON -Werror=dev .. '
 
   - task: CMake@1
     name: Build

tests/CMakeLists.txt

@@ -9,6 +9,10 @@ include(ExternalProject)
 # will make visual studio generated project group files
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 
+if(CI_TESTING AND GSL_CXX_STANDARD EQUAL 20)
+    add_compile_definitions(FORCE_STD_SPAN_TESTS=1)
+endif()
+
 if(IOS)
     add_compile_definitions(GTEST_HAS_DEATH_TEST=1 IOS_PROCESS_DELAY_WORKAROUND=1)
 endif()
@@ -54,7 +58,7 @@ if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
     find_package(Microsoft.GSL REQUIRED)
 endif()
 
-if (MSVC AND (GSL_CXX_STANDARD EQUAL 17))
+if (MSVC AND (GSL_CXX_STANDARD GREATER_EQUAL 17))
     set(GSL_CPLUSPLUS_OPT -Zc:__cplusplus -permissive-)
 endif()
 
@@ -135,6 +139,11 @@ else()
           $<$<AND:$<VERSION_GREATER:$<CXX_COMPILER_VERSION>,4.99>,$<VERSION_LESS:$<CXX_COMPILER_VERSION>,6>>:
             $<$<EQUAL:${GSL_CXX_STANDARD},17>:-Wno-undefined-func-template>
           >
+          $<$<AND:$<EQUAL:${GSL_CXX_STANDARD},20>,$<CXX_COMPILER_VERSION:11.0.0>>:
+              -Wno-zero-as-null-pointer-constant  # failing Clang Ubuntu 20.04 tests, seems to be a bug with clang 11.0.0
+                                                  # (operator< is being re-written by the compiler as operator<=> and
+                                                  # raising the warning)
+          >
         >
         $<$<CXX_COMPILER_ID:AppleClang>:
           $<$<AND:$<VERSION_GREATER:$<CXX_COMPILER_VERSION>,9.1>,$<VERSION_LESS:$<CXX_COMPILER_VERSION>,10>>:

tests/algorithm_tests.cpp

@@ -27,7 +27,6 @@ namespace gsl
 struct fail_fast;
 } // namespace gsl
 
-using namespace std;
 using namespace gsl;
 
 TEST(algorithm_tests, same_type)
@@ -73,8 +72,8 @@ TEST(algorithm_tests, same_type)
         std::array<int, 5> src{1, 2, 3, 4, 5};
         std::array<int, 10> dst{};
 
-        const span<int> src_span(src);
+        const gsl::span<int> src_span(src);
-        const span<int, 10> dst_span(dst);
+        const gsl::span<int, 10> dst_span(dst);
 
         copy(src_span, dst_span);
         copy(src_span, dst_span.subspan(src_span.size()));

tests/at_tests.cpp

@@ -119,7 +119,7 @@ TEST(at_tests, InitializerList)
     EXPECT_DEATH(gsl::at({1, 2, 3, 4}, 4), expected);
 }
 
-#if defined(__cplusplus) && __cplusplus >= 202002L
+#if defined(FORCE_STD_SPAN_TESTS) || defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
 TEST(at_tests, std_span)
 {
     std::vector<int> vec{1, 2, 3, 4, 5};
@@ -128,18 +128,24 @@ TEST(at_tests, std_span)
     std::vector<int> cvec{1, 2, 3, 4, 5};
     std::span csp{cvec};
 
-    for (size_t i = 0, i < vec.size(); ++i)
+    for (gsl::index i = 0; i < gsl::narrow_cast<gsl::index>(vec.size()); ++i)
     {
-        EXPECT_TRUE(&gsl::at(sp, i) == &vec[i]);
+        EXPECT_TRUE(&gsl::at(sp, i) == &vec[gsl::narrow_cast<size_t>(i)]);
-        EXPECT_TRUE(&gsl::at(csp, i) == &cvec[i]);
+        EXPECT_TRUE(&gsl::at(csp, i) == &cvec[gsl::narrow_cast<size_t>(i)]);
     }
 
+    const auto terminateHandler = std::set_terminate([] {
+        std::cerr << "Expected Death. std_span";
+        std::abort();
+    });
+    const auto expected = GetExpectedDeathString(terminateHandler);
+
     EXPECT_DEATH(gsl::at(sp, -1), expected);
-    EXPECT_DEATH(gsl::at(sp, sp.size()), expected);
+    EXPECT_DEATH(gsl::at(sp, gsl::narrow_cast<gsl::index>(sp.size())), expected);
     EXPECT_DEATH(gsl::at(csp, -1), expected);
-    EXPECT_DEATH(gsl::at(csp, sp.size()), expected);
+    EXPECT_DEATH(gsl::at(csp, gsl::narrow_cast<gsl::index>(sp.size())), expected);
 }
-#endif // __cplusplus >= 202002L
+#endif // defined(FORCE_STD_SPAN_TESTS) || defined(__cpp_lib_span) && __cpp_lib_span >= 202002L
 
 #if !defined(_MSC_VER) || defined(__clang__) || _MSC_VER >= 1910
 static constexpr bool test_constexpr()

tests/span_compatibility_tests.cpp

@@ -55,14 +55,14 @@ void ArrayConvertibilityCheck()
         EXPECT_TRUE(sp_const_nullptr_1.data() == stl_nullptr.data());
         EXPECT_TRUE(sp_const_nullptr_1.size() == 3);
 
-        span<const T* const> sp_const_nullptr_2{std::as_const(stl_nullptr)};
+        gsl::span<const T* const> sp_const_nullptr_2{std::as_const(stl_nullptr)};
         EXPECT_TRUE(sp_const_nullptr_2.data() == stl_nullptr.data());
         EXPECT_TRUE(sp_const_nullptr_2.size() == 3);
 
-        static_assert(std::is_same<decltype(span{stl_nullptr}), span<T*, 3>>::value,
+        static_assert(std::is_same<decltype(gsl::span{stl_nullptr}), gsl::span<T*, 3>>::value,
                       "std::is_same< decltype(span{stl_nullptr}), span<T*, 3>>::value");
         static_assert(
-            std::is_same<decltype(span{std::as_const(stl_nullptr)}), span<T* const, 3>>::value,
+            std::is_same<decltype(gsl::span{std::as_const(stl_nullptr)}), gsl::span<T* const, 3>>::value,
             "std::is_same< decltype(span{std::as_const(stl_nullptr)}), span<T* const, "
             "3>>::value");
     }

tests/span_ext_tests.cpp

@@ -48,7 +48,7 @@ TEST(span_ext_test, make_span_from_pointer_length_constructor)
 
     {
         int* p = nullptr;
-        auto s = make_span(p, narrow_cast<span<int>::size_type>(0));
+        auto s = make_span(p, narrow_cast<gsl::span<int>::size_type>(0));
         EXPECT_TRUE(s.size() == 0);
         EXPECT_TRUE(s.data() == nullptr);
     }
@@ -136,9 +136,9 @@ TEST(span_ext_test, make_span_from_std_array_constructor)
 
     // This test checks for the bug found in gcc 6.1, 6.2, 6.3, 6.4, 6.5 7.1, 7.2, 7.3 - issue #590
     {
-        span<int> s1 = make_span(arr);
+        gsl::span<int> s1 = make_span(arr);
 
-        static span<int> s2;
+        static gsl::span<int> s2;
         s2 = s1;
 
 #if defined(__GNUC__) && __GNUC__ == 6 && (__GNUC_MINOR__ == 4 || __GNUC_MINOR__ == 5) &&          \
@@ -194,7 +194,7 @@ TEST(span_ext_test, make_span_from_container_constructor)
 TEST(span_test, interop_with_gsl_at)
 {
     int arr[5] = {1, 2, 3, 4, 5};
-    span<int> s{arr};
+    gsl::span<int> s{arr};
     EXPECT_TRUE(at(s, 0) == 1);
     EXPECT_TRUE(at(s, 1) == 2);
 }
@@ -202,7 +202,7 @@ TEST(span_test, interop_with_gsl_at)
 TEST(span_ext_test, iterator_free_functions)
 {
     int a[] = {1, 2, 3, 4};
-    span<int> s{a};
+    gsl::span<int> s{a};
 
     EXPECT_TRUE((std::is_same<decltype(s.begin()), decltype(begin(s))>::value));
     EXPECT_TRUE((std::is_same<decltype(s.end()), decltype(end(s))>::value));
@@ -232,7 +232,7 @@ TEST(span_ext_test, iterator_free_functions)
 TEST(span_ext_test, ssize_free_function)
 {
     int a[] = {1, 2, 3, 4};
-    span<int> s{a};
+    gsl::span<int> s{a};
 
     EXPECT_FALSE((std::is_same<decltype(s.size()), decltype(ssize(s))>::value));
     EXPECT_TRUE(s.size() == static_cast<std::size_t>(ssize(s)));
@@ -242,8 +242,8 @@ TEST(span_ext_test, ssize_free_function)
 TEST(span_ext_test, comparison_operators)
 {
     {
-        span<int> s1;
+        gsl::span<int> s1;
-        span<int> s2;
+        gsl::span<int> s2;
         EXPECT_TRUE(s1 == s2);
         EXPECT_FALSE(s1 != s2);
         EXPECT_FALSE(s1 < s2);
@@ -260,8 +260,8 @@ TEST(span_ext_test, comparison_operators)
 
     {
         int arr[] = {2, 1};
-        span<int> s1 = arr;
+        gsl::span<int> s1 = arr;
-        span<int> s2 = arr;
+        gsl::span<int> s2 = arr;
 
         EXPECT_TRUE(s1 == s2);
         EXPECT_FALSE(s1 != s2);
@@ -280,8 +280,8 @@ TEST(span_ext_test, comparison_operators)
     {
         int arr[] = {2, 1}; // bigger
 
-        span<int> s1;
+        gsl::span<int> s1;
-        span<int> s2 = arr;
+        gsl::span<int> s2 = arr;
 
         EXPECT_TRUE(s1 != s2);
         EXPECT_TRUE(s2 != s1);
@@ -300,8 +300,8 @@ TEST(span_ext_test, comparison_operators)
     {
         int arr1[] = {1, 2};
         int arr2[] = {1, 2};
-        span<int> s1 = arr1;
+        gsl::span<int> s1 = arr1;
-        span<int> s2 = arr2;
+        gsl::span<int> s2 = arr2;
 
         EXPECT_TRUE(s1 == s2);
         EXPECT_FALSE(s1 != s2);
@@ -320,8 +320,8 @@ TEST(span_ext_test, comparison_operators)
     {
         int arr[] = {1, 2, 3};
 
-        span<int> s1 = {&arr[0], 2}; // shorter
+        gsl::span<int> s1 = {&arr[0], 2}; // shorter
-        span<int> s2 = arr;          // longer
+        gsl::span<int> s2 = arr;          // longer
 
         EXPECT_TRUE(s1 != s2);
         EXPECT_TRUE(s2 != s1);
@@ -341,8 +341,8 @@ TEST(span_ext_test, comparison_operators)
         int arr1[] = {1, 2}; // smaller
         int arr2[] = {2, 1}; // bigger
 
-        span<int> s1 = arr1;
+        gsl::span<int> s1 = arr1;
-        span<int> s2 = arr2;
+        gsl::span<int> s2 = arr2;
 
         EXPECT_TRUE(s1 != s2);
         EXPECT_TRUE(s2 != s1);

tests/span_tests.cpp

@@ -43,7 +43,6 @@
 
 #include "deathTestCommon.h"
 
-using namespace std;
 using namespace gsl;
 
 namespace
@@ -1085,7 +1084,7 @@ TEST(span_test, as_bytes)
 
     int b[5] = {1, 2, 3, 4, 5};
     {
-        span<int> sp(begin(b), static_cast<size_t>(-2));
+        span<int> sp(std::begin(b), static_cast<size_t>(-2));
         EXPECT_DEATH((void) sp.size_bytes(), expected);
     }
 }

tests/string_span_tests.cpp

@@ -30,7 +30,6 @@
 
 #include "deathTestCommon.h"
 
-using namespace std;
 using namespace gsl;
 
 // Generic string functions