[{"id":3684918,"web_url":"http://patchwork.ozlabs.org/comment/3684918/","msgid":"","list_archive_url":null,"date":"2026-04-30T19:52:19","subject":"Re: [PATCH] libsdc++: Remove duplicated\n __mdspan::__is_constant_wrapper.","submitter":{"id":48004,"url":"http://patchwork.ozlabs.org/api/people/48004/","name":"Jonathan Wakely","email":"jwakely@redhat.com"},"content":"On Thu, 30 Apr 2026 at 19:19, Tomasz Kamiński wrote:\n>\n> Replaced it with std::__is_constant_wrapper_v from utility.\n>\n> libstdc++-v3/ChangeLog:\n>\n> * include/std/mdspan: Replace eight spaces with tabs.\n> (__mdspan::__is_constant_wrapper): Remove.\n> (__mdspan::__acceptable_slice_type, __mdspan::__static_slice_extent)\n> (__mdspan::__is_unit_stride_slice, __mdspan::__canonical_range_slice)\n> (__mdspan::__check_inrange_index, __mdspan::__check_valid_index)\n> (__mdspan::__check_valid_slice, std::submdspan): Replace\n> __mdspan::__is_constant_wrapper with std::__is_constant_wrapper_v.\n> ---\n> Testing on x86_64-linux. *mdspan* test already passed.\n> OK for trunk?\n\nTypo for \"libstdc++\" in the subject line. OK with that fixed.\n\n\n>\n> libstdc++-v3/include/std/mdspan | 69 +++++++++++++++------------------\n> 1 file changed, 31 insertions(+), 38 deletions(-)\n>\n> diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan\n> index a3ab64633ac..5938bf09a94 100644\n> --- a/libstdc++-v3/include/std/mdspan\n> +++ b/libstdc++-v3/include/std/mdspan\n> @@ -838,7 +838,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n>\n> template\n> constexpr bool __is_padded_mapping = __is_left_padded_mapping<_Mapping>\n> - || __is_right_padded_mapping<_Mapping>;\n> + || __is_right_padded_mapping<_Mapping>;\n> #endif\n>\n> template\n> @@ -904,13 +904,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> && std::cmp_less_equal(__value, __max);\n> }\n>\n> - template\n> - constexpr bool __is_constant_wrapper = false;\n> -\n> - template<_CwFixedValue _Xv, typename _Tp>\n> - constexpr bool __is_constant_wrapper>\n> - = true;\n> -\n> template\n> constexpr auto\n> __extract_extent(const _Extents& __exts)\n> @@ -922,7 +915,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n>\n> template\n> concept __acceptable_slice_type = same_as<_Slice, full_extent_t>\n> - || same_as<_Slice, _IndexType> || __is_constant_wrapper<_Slice>\n> + || same_as<_Slice, _IndexType> || __is_constant_wrapper_v<_Slice>\n> || __is_extent_slice<_Slice>;\n>\n> template\n> @@ -1003,7 +996,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> return _Extent;\n> else if constexpr (same_as<_Slice, constant_wrapper<_IndexType(0)>>)\n> return 0;\n> - else if constexpr (__is_constant_wrapper)\n> + else if constexpr (__is_constant_wrapper_v)\n> return _Slice::extent_type::value;\n> else\n> return dynamic_extent;\n> @@ -1204,7 +1197,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n>\n> template\n> concept __is_unit_stride_slice = (__mdspan::__is_extent_slice<_Slice>\n> - && __mdspan::__is_constant_wrapper\n> + && __is_constant_wrapper_v\n> && _Slice::stride_type::value == 1)\n> || std::same_as<_Slice, full_extent_t>;\n>\n> @@ -1534,7 +1527,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> template\n> requires is_constructible_v\n> constexpr explicit(!(extents_type::rank() == 0\n> - && is_convertible_v<_OExtents, extents_type>))\n> + && is_convertible_v<_OExtents, extents_type>))\n> mapping(const layout_stride::mapping<_OExtents>& __other) noexcept\n> : mapping(__other.extents(), __mdspan::__internal_ctor{})\n> { __glibcxx_assert(*this == __other); }\n> @@ -1710,7 +1703,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> template\n> requires is_constructible_v\n> constexpr explicit(!(extents_type::rank() == 0\n> - && is_convertible_v<_OExtents, extents_type>))\n> + && is_convertible_v<_OExtents, extents_type>))\n> mapping(const layout_stride::mapping<_OExtents>& __other) noexcept\n> : mapping(__other.extents(), __mdspan::__internal_ctor{})\n> { __glibcxx_assert(*this == __other); }\n> @@ -3308,10 +3301,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> .extent = __span,\n> .stride = cw<_IndexType(1)>\n> };\n> - else if constexpr (__is_constant_wrapper<_StrideType>)\n> - {\n> + else if constexpr (__is_constant_wrapper_v<_StrideType>)\n> + {\n> static_assert(_StrideType::value > 0);\n> - if constexpr (__is_constant_wrapper<_SpanType>)\n> + if constexpr (__is_constant_wrapper_v<_SpanType>)\n> return extent_slice{\n> .offset = __offset,\n> .extent = cw<_IndexType(1 + (_SpanType::value - 1) / _StrideType::value)>,\n> @@ -3323,7 +3316,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> .extent = _IndexType(__span > 0 ? 1 + (__span - 1) / _StrideType::value : 0),\n> .stride = __stride\n> };\n> - }\n> + }\n> else if (__span == 0 || __stride == 1)\n> return extent_slice{\n> .offset = __offset,\n> @@ -3331,7 +3324,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> .stride = _IndexType(1)\n> };\n> else\n> - {\n> + {\n> __glibcxx_assert(__stride > 0);\n> return extent_slice{\n> .offset = __offset,\n> @@ -3386,7 +3379,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> __check_inrange_index(const extents<_IndexType, _Extent>& __ext,\n> const _OIndexType& __idx)\n> {\n> - if constexpr (__is_constant_wrapper<_OIndexType>\n> + if constexpr (__is_constant_wrapper_v<_OIndexType>\n> && _Extent != dynamic_extent)\n> {\n> static_assert(_OIndexType::value >= 0);\n> @@ -3401,7 +3394,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> __check_valid_index(const extents<_IndexType, _Extent>& __ext,\n> const _OIndexType& __idx)\n> {\n> - if constexpr (__is_constant_wrapper<_OIndexType>\n> + if constexpr (__is_constant_wrapper_v<_OIndexType>\n> && _Extent != dynamic_extent)\n> {\n> static_assert(_OIndexType::value >= 0);\n> @@ -3427,31 +3420,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> constant_wrapper<_IndexType(0)>>)\n> __mdspan::__check_valid_index(__ext, __slice.offset);\n> else if constexpr (is_same_v - constant_wrapper<_IndexType(1)>>)\n> - __mdspan::__check_inrange_index(__ext, __slice.offset);\n> - else if constexpr (__is_constant_wrapper)\n> + constant_wrapper<_IndexType(1)>>)\n> + __mdspan::__check_inrange_index(__ext, __slice.offset);\n> + else if constexpr (__is_constant_wrapper_v)\n> {\n> - __mdspan::__check_inrange_index(__ext, __slice.offset);\n> - if constexpr (__is_constant_wrapper)\n> + __mdspan::__check_inrange_index(__ext, __slice.offset);\n> + if constexpr (__is_constant_wrapper_v)\n> static_assert(_Slice::stride_type::value > 0);\n> else\n> __glibcxx_assert(__slice.stride > 0);\n>\n> if constexpr (_Extent != dynamic_extent\n> - && __is_constant_wrapper)\n> - static_assert(std::cmp_greater_equal(\n> + && __is_constant_wrapper_v)\n> + static_assert(std::cmp_greater_equal(\n> _Extent - _Slice::offset_type::value,\n> _Slice::extent_type::value));\n> if constexpr (_Extent != dynamic_extent\n> - && __is_constant_wrapper)\n> - static_assert(std::cmp_greater(\n> + && __is_constant_wrapper_v)\n> + static_assert(std::cmp_greater(\n> _Extent,\n> (_Slice::extent_type::value - 1) * _Slice::stride_type::value));\n>\n> if constexpr (_Extent != dynamic_extent\n> - && __is_constant_wrapper\n> - && __is_constant_wrapper)\n> - static_assert(std::cmp_greater(\n> + && __is_constant_wrapper_v\n> + && __is_constant_wrapper_v)\n> + static_assert(std::cmp_greater(\n> _Extent - _Slice::offset_type::value,\n> (_Slice::extent_type::value - 1) * _Slice::stride_type::value));\n> else\n> @@ -3460,18 +3453,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> (_Slice::extent_type::value - 1) * __slice.stride));\n> }\n> else if constexpr (is_same_v - constant_wrapper<_IndexType(1)>>)\n> + constant_wrapper<_IndexType(1)>>)\n> {\n> - __mdspan::__check_valid_index(__ext, __slice.offset);\n> + __mdspan::__check_valid_index(__ext, __slice.offset);\n> __glibcxx_assert(std::cmp_greater_equal(\n> __ext.extent(0) - __slice.offset,\n> __slice.extent));\n> - }\n> + }\n> else if (__slice.extent == 0)\n> __mdspan::__check_valid_index(__ext, __slice.offset);\n> else\n> {\n> - __glibcxx_assert(__slice.offset < __ext.extent(0));\n> + __glibcxx_assert(__slice.offset < __ext.extent(0));\n> __glibcxx_assert(__slice.extent == 1 || __slice.stride > 0);\n> __glibcxx_assert(__slice.extent == 1 || std::cmp_greater(\n> __ext.extent(0) - __slice.offset,\n> @@ -3479,7 +3472,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> }\n> }\n> else if constexpr (!is_same_v<_Slice, full_extent_t>)\n> - __mdspan::__check_inrange_index(__ext, __slice);\n> + __mdspan::__check_inrange_index(__ext, __slice);\n> }\n>\n> template\n> @@ -3548,7 +3541,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION\n> typename _Accessor, typename... _RawSlices>\n> requires (sizeof...(_RawSlices) == _Extents::rank()\n> && __mdspan::__sliceable_mapping,\n> - __mdspan::__full_extent_t<_RawSlices>...>)\n> + __mdspan::__full_extent_t<_RawSlices>...>)\n> constexpr auto\n> submdspan(\n> const mdspan<_ElementType, _Extents, _Layout, _Accessor>& __md,\n> --\n> 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