On Wed, 17 Dec 2025 at 20:52, Luc Grosheintz <[email protected]> wrote:
>
> On Solaris, same_as<int8_t, char> is true. Therefore, int8_t isn't a
> valid IndexType, because char is neither a signed nor an unsigned
> integer type.
>
> This commit fixes the tests by avoiding int8_t (and uint8_t) by using
> 'signed char' (and 'unsigned char').
>
> PR libstdc++/123176
>
> libstdc++-v3/ChangeLog:
>
> *
> testsuite/23_containers/mdspan/submdspan/submdspan_canonicalize_slices_neg.cc:
> Avoid
> int8_t with signed char.
>
> Signed-off-by: Luc Grosheintz <[email protected]>
> ---
>
> This fix is purely based on a theoretical understanding of the compiler
> messages reported in the bug report. Unfortunately, I don't have access
> to a Solaris machine; and therefore am not able to test on Solaris. I
> have tested on linux-x86_64.
>
> I've CC'ed Rainer Orth who reported the issue, maybe Rainer's willing
> and has time to test it on Solaris.
>
> .../submdspan_canonicalize_slices_neg.cc | 32 +++++++++++--------
> 1 file changed, 18 insertions(+), 14 deletions(-)
>
> diff --git
> a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_canonicalize_slices_neg.cc
>
> b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_canonicalize_slices_neg.cc
> index 94bca183aa3..0098547d750 100644
> ---
> a/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_canonicalize_slices_neg.cc
> +++
> b/libstdc++-v3/testsuite/23_containers/mdspan/submdspan/submdspan_canonicalize_slices_neg.cc
> @@ -8,9 +8,12 @@ constexpr size_t dyn = std::dynamic_extent;
> constexpr auto dyn_empty = std::extents<int32_t, dyn>{0};
> constexpr auto sta_empty = std::extents<uint32_t, 0>{};
>
> -constexpr auto dyn_uexts = std::extents<uint8_t, dyn>{5};
> +// On Solaris same_as<int8_t, char> is true. Therefore, int8_t is not a
> signed
> +// or unsigned integer type and hence not a valid IndexType. We'll use signed
> +// char and unsigned char for int8_t throughout.
An alternative fix would be to make char a signed integer type on
Solaris, so that int8_t is a signed integer type, and it can be used
here, and with std::cmp_less, etc.
But that would break other things, where char is supposed to be
excluded from the valid types.
It's hard to know which kind of non-conformance is worse.
The patch looks fine to me though.
> +constexpr auto dyn_uexts = std::extents<unsigned char, dyn>{5};
> constexpr auto sta_uexts = std::extents<uint16_t, 5>{5};
> -constexpr auto dyn_sexts = std::extents<int8_t, dyn>{5};
> +constexpr auto dyn_sexts = std::extents<signed char, dyn>{5};
> constexpr auto sta_sexts = std::extents<int16_t, 5>{5};
>
> constexpr bool
> @@ -69,7 +72,7 @@ template<typename Offset, typename Extent, typename Stride,
> typename Extents>
> return true;
> }
>
> -constexpr auto i8_1 = int8_t{1};
> +constexpr auto i8_1 = (signed char){1};
>
> static_assert(test_under2(-i8_1, 0, 1, dyn_uexts)); // { dg-error
> "expansion of" }
> static_assert(test_under2(0, -i8_1, 1, dyn_uexts)); // { dg-error
> "expansion of" }
> @@ -84,7 +87,7 @@ static_assert(test_under2(-i8_1, 0, 1, sta_sexts)); // {
> dg-error "expansion o
> static_assert(test_under2(0, -i8_1, 1, sta_sexts)); // { dg-error
> "expansion of" }
> static_assert(test_under2(0, 1, -i8_1, sta_sexts)); // { dg-error
> "expansion of" }
>
> -constexpr auto c_i8_m1 = std::cw<int8_t{-1}>;
> +constexpr auto c_i8_m1 = std::cw<(signed char){-1}>;
> constexpr auto c_i16_m1 = std::cw<int16_t{-1}>;
> constexpr auto c_i64_m1 = std::cw<int64_t{-1}>;
>
> @@ -109,8 +112,8 @@ template<typename Offset, typename Extent, typename
> Stride, typename Extents>
> return true;
> }
>
> -constexpr auto i8_6 = int8_t{6};
> -constexpr auto c_i8_6 = std::cw<int8_t{6}>;
> +constexpr auto i8_6 = (signed char){6};
> +constexpr auto c_i8_6 = std::cw<(signed char){6}>;
> constexpr auto c2 = std::cw<2>;
> constexpr auto c4 = std::cw<4>;
>
> @@ -155,21 +158,22 @@ static_assert(test_over2(c2, c4, 1, sta_sexts)); //
> { dg-error "expansion of
> constexpr bool
> test_overflow1(auto o, auto e)
> {
> - auto exts = std::extents<uint8_t, dyn>{255};
> + auto exts = std::extents<unsigned char, dyn>{std::numeric_limits<unsigned
> char>::max()};
> auto slice = std::strided_slice{o, e, 1};
> std::submdspan_canonicalize_slices(exts, slice);
> return true;
> }
>
> -static_assert(test_overflow1(128, 128)); // { dg-error
> "expansion of" }
> -static_assert(test_overflow1(std::cw<128>, 128)); // { dg-error
> "expansion of" }
> -static_assert(test_overflow1(128, std::cw<128>)); // { dg-error
> "expansion of" }
> -static_assert(test_overflow1(std::cw<128>, std::cw<128>)); // { dg-error
> "expansion of" }
> +constexpr int half_max = std::numeric_limits<unsigned char>::max() / 2 + 1;
> +static_assert(test_overflow1(half_max, half_max)); // {
> dg-error "expansion of" }
> +static_assert(test_overflow1(std::cw<half_max>, half_max)); // {
> dg-error "expansion of" }
> +static_assert(test_overflow1(half_max, std::cw<half_max>)); // {
> dg-error "expansion of" }
> +static_assert(test_overflow1(std::cw<half_max>, std::cw<half_max>)); // {
> dg-error "expansion of" }
>
> constexpr bool
> test_overflow2(auto b, auto e)
> {
> - auto exts = std::extents<uint8_t, dyn>{255};
> + auto exts = std::extents<unsigned char, dyn>{std::numeric_limits<unsigned
> char>::max()};
> auto slice = std::pair{b, e};
> std::submdspan_canonicalize_slices(exts, slice);
> return true;
> @@ -180,8 +184,8 @@ static_assert(test_overflow2(std::cw<5>, 4));
> // { dg-error "expansion
> static_assert(test_overflow2(5, std::cw<4>)); // { dg-error
> "expansion of" }
> static_assert(test_overflow2(std::cw<5>, std::cw<4>)); // { dg-error
> "expansion of" }
>
> -constexpr auto u8_4 = uint8_t{4};
> -constexpr auto u8_5 = uint8_t{5};
> +constexpr auto u8_4 = (unsigned char){4};
> +constexpr auto u8_5 = (unsigned char){5};
> static_assert(test_overflow2(u8_5, u8_4)); // { dg-error
> "expansion of" }
> static_assert(test_overflow2(std::cw<u8_5>, u8_4)); // { dg-error
> "expansion of" }
> static_assert(test_overflow2(u8_5, std::cw<u8_4>)); // { dg-error
> "expansion of" }
> --
> 2.52.0
>
