As in title. Repro:
#include <mdspan>
#include <ranges>
using namespace std;
class DummyAccessor {
public:
using element_type = int;
using reference = int;
using offset_policy = DummyAccessor;
struct data_handle_type {};
reference access(data_handle_type, size_t);
data_handle_type offset(data_handle_type, size_t);
};
class DummyIterator {
public:
using value_type = int;
using difference_type = ptrdiff_t;
DummyIterator() = default;
DummyIterator &operator++();
DummyIterator operator++(int);
value_type operator*() const;
bool operator==(const DummyIterator &) const;
};
using MDS = mdspan<int, dextents<int, 1>, layout_left, DummyAccessor>;
using View = decltype(declval<ranges::subrange<DummyIterator>>() |
views::enumerate | views::chunk(2));
static_assert(sizeof(MDS) == sizeof(int)); // single dynamic extent
static_assert(sizeof(ranges::iterator_t<View>) == 3 * sizeof(ptrdiff_t)); // three pointersEDG and Clang interpret [[no_unique_address]] differently from MSVC. Command line:
PS E:\no_unique_address> cl /Zs /nologo /std:c++23preview .\bug.cpp
bug.cpp
PS E:\no_unique_address> clang-cl /Zs /nologo /std:c++23preview .\bug.cpp
.\bug.cpp(33,15): error: static assertion failed due to requirement 'sizeof(std::mdspan<int, std::extents<int, 18446744073709551615>,
std::layout_left, DummyAccessor>) == sizeof(int)'
33 | static_assert(sizeof(MDS) == sizeof(int));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
.\bug.cpp(33,27): note: expression evaluates to '8 == 4'
33 | static_assert(sizeof(MDS) == sizeof(int));
| ~~~~~~~~~~~~^~~~~~~~~~~~~~
.\bug.cpp(34,15): error: static assertion failed due to requirement
'sizeof(std::ranges::chunk_view<std::ranges::enumerate_view<std::ranges::subrange<DummyIterator, DummyIterator,
std::ranges::subrange_kind::unsized>>>::_Iterator<true>) == 3 * sizeof(long long)'
34 | static_assert(sizeof(ranges::iterator_t<View>) == 3 * sizeof(ptrdiff_t));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\bug.cpp(34,48): note: expression evaluates to '32 == 24'
34 | static_assert(sizeof(ranges::iterator_t<View>) == 3 * sizeof(ptrdiff_t));
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
2 errors generated.
PS E:\no_unique_address> cl /Zs /nologo /std:c++23preview .\bug.cpp /BE
bug.cpp
".\bug.cpp", line 33: error: static assertion failed
static_assert(sizeof(MDS) == sizeof(int));
^
".\bug.cpp", line 33: note: the final comparison was 8 == 4
static_assert(sizeof(MDS) == sizeof(int));
^
".\bug.cpp", line 34: error: static assertion failed
static_assert(sizeof(ranges::iterator_t<View>) == 3 * sizeof(ptrdiff_t));
^
".\bug.cpp", line 34: note: the final comparison was 32 == 24
static_assert(sizeof(ranges::iterator_t<View>) == 3 * sizeof(ptrdiff_t));Introduced in #4960.
As in title. Repro:
EDG and Clang interpret
[[no_unique_address]]differently from MSVC. Command line:Introduced in #4960.