testing one of CaseyCarter's comments

This commit is contained in:
Jordan Maples 2020-04-09 17:33:33 -07:00
parent ffbfcc0a9f
commit efbce17ca4

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@ -43,42 +43,31 @@ static_assert(!std::is_convertible<Derived (*)[], Base (*)[]>::value,
"!std::is_convertible<Derived(*)[], Base(*)[]>");
// int*(*) [], int const* const(*)[] was identified as an issue in CWG330 and the resolution was
// provided with N4261. The changes were not backported to all versions of the compilers that GSL
// supports. The `if constexpr` should prevent codegen from happening if it is not supported however
// a few compilers continue to complain about the logic within. Filtering g++ version < 8, clang
// version < 7, and XCode 9.4 and 10.1 which looks to be Apple clang versions 9.1 and 10.0.
#if (defined(_MSC_VER)) || (defined(__GNUC__) && __GNUC__ > 7) || \
(defined(__APPLE__) && defined(__clang_major__) && __clang_major__ > 10) || \
(!defined(__APPLE__) && defined(__clang__) && __clang_major__ > 6)
template <class = void>
// provided with N4261.
template <class T = int>
void ArrayConvertibilityCheck()
{
#if __cplusplus >= 201703l
if constexpr (std::is_convertible<int*(*) [], int const* const(*)[]>::value)
if constexpr (std::is_convertible<T*(*) [], T const* const(*)[]>::value)
{
std::array<int*, 3> stl_nullptr{{nullptr, nullptr, nullptr}};
gsl::span<const int* const> sp_const_nullptr_1{stl_nullptr};
std::array<T*, 3> stl_nullptr{{nullptr, nullptr, nullptr}};
gsl::span<const T* const> sp_const_nullptr_1{stl_nullptr};
EXPECT_TRUE(sp_const_nullptr_1.data() == stl_nullptr.data());
EXPECT_TRUE(sp_const_nullptr_1.size() == 3);
span<const int* const> sp_const_nullptr_2{std::as_const(stl_nullptr)};
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<int*, 3>>::value,
"std::is_same< decltype(span{stl_nullptr}), span<int*, 3>>::value");
static_assert(std::is_same<decltype(span{stl_nullptr}), 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<int* const, 3>>::value,
"std::is_same< decltype(span{std::as_const(stl_nullptr)}), span<int* const, "
std::is_same<decltype(span{std::as_const(stl_nullptr)}), span<T* const, 3>>::value,
"std::is_same< decltype(span{std::as_const(stl_nullptr)}), span<T* const, "
"3>>::value");
}
#endif
}
#else
template <class = void>
void ArrayConvertibilityCheck()
{}
#endif
TEST(span_compatibility_tests, assertion_tests)
{