LGTM. I know that CTAD wasn't provided due to heavy header considerations. But wouldn't providing CTAD be an enhancement? At least in terms of user convenience.
Tomasz Kamiński <[email protected]> 於 2025年11月15日 週六 上午1:06寫道： > Previously, _Utf_view accepted any input_range, including > reference-to-array > types like char(&)[2], and stored it as the _M_base member. In such cases, > _Utf_view was not assignable, failing the requirement to be a view > concept. > > This patch addresses the issue by adding the ranges::view constraint to the > second template parameter of _Utf_view, and for clarity renaming it from > _Range to _View. The constructor is also adjusted to accept its argument > by value (views must be O(1) move-constructible). This prevents implicitly > generated CTAD from deducing a reference type. > > This makes _Utf_view consistent with both other standard views and the > wording from P2728R8: Unicode in the Library, Part 1: UTF Transcoding [1]. > > The explicit CTAD from viewable_range is not defined for _Utf_view because > it depends on views::all_t, views::ref_view, and views::owning_view, > which are declared in <ranges>. Consequently, users must explicitly cast > the argument to a view or specify it as a template parameter. > > [1] https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p2728r8.html > > libstdc++-v3/ChangeLog: > > * include/bits/unicode.h (_Utf_view): Rename the template parameter > from _Range to _View and constrain it with ranges::view. > (_Utf_view::_Utf_view): Accept by value instead of rvalue > reference. > * include/std/format (__format::__write_padded): Replace _Utf_view > over const char32_t(&)[1] with span<const char32_t, 1>. > * testsuite/ext/unicode/view.cc: Add checks if specialization > of _Utf_view satisfy view. Wrap arrays into std::span before > cosntructing _Utf_view. > --- > libstdc++-v3/include/bits/unicode.h | 15 ++++++++------- > libstdc++-v3/include/std/format | 2 +- > libstdc++-v3/testsuite/ext/unicode/view.cc | 16 ++++++++++------ > 3 files changed, 19 insertions(+), 14 deletions(-) > > diff --git a/libstdc++-v3/include/bits/unicode.h > b/libstdc++-v3/include/bits/unicode.h > index 44872db4ed6..09f7c2d7bfb 100644 > --- a/libstdc++-v3/include/bits/unicode.h > +++ b/libstdc++-v3/include/bits/unicode.h > @@ -695,13 +695,14 @@ namespace __unicode > friend class _Utf_iterator; > }; > > - template<typename _ToFormat, ranges::input_range _Range> > + template<typename _ToFormat, ranges::input_range _View> > + requires ranges::view<_View> > class _Utf_view > - : public ranges::view_interface<_Utf_view<_ToFormat, _Range>> > + : public ranges::view_interface<_Utf_view<_ToFormat, _View>> > { > - using _Iterator = _Utf_iterator<ranges::range_value_t<_Range>, > - _ToFormat, > ranges::iterator_t<_Range>, > - ranges::sentinel_t<_Range>>; > + using _Iterator = _Utf_iterator<ranges::range_value_t<_View>, > + _ToFormat, ranges::iterator_t<_View>, > + ranges::sentinel_t<_View>>; > > template<typename _Iter, typename _Sent> > constexpr auto > @@ -725,11 +726,11 @@ namespace __unicode > return _Iterator(__last, __last); > } > > - _Range _M_base; > + _View _M_base; > > public: > constexpr explicit > - _Utf_view(_Range&& __r) : _M_base(std::forward<_Range>(__r)) { } > + _Utf_view(_View __r) : _M_base(std::move(__r)) { } > > constexpr auto begin() > { return _M_begin(ranges::begin(_M_base), ranges::end(_M_base)); } > diff --git a/libstdc++-v3/include/std/format > b/libstdc++-v3/include/std/format > index 1102ac8f6e8..f64f35a202e 100644 > --- a/libstdc++-v3/include/std/format > +++ b/libstdc++-v3/include/std/format > @@ -845,7 +845,7 @@ namespace __format > { > // Encode fill char as multiple code units of type _CharT. > const char32_t __arr[1]{ __fill_char }; > - _Utf_view<_CharT, const char32_t(&)[1]> __v(__arr); > + _Utf_view<_CharT, span<const char32_t, 1>> __v(__arr); > basic_string<_CharT> __padstr(__v.begin(), __v.end()); > __padding = __padstr; > while (__l-- > 0) > diff --git a/libstdc++-v3/testsuite/ext/unicode/view.cc > b/libstdc++-v3/testsuite/ext/unicode/view.cc > index 40c8fcf34fb..677a21d8c1f 100644 > --- a/libstdc++-v3/testsuite/ext/unicode/view.cc > +++ b/libstdc++-v3/testsuite/ext/unicode/view.cc > @@ -7,6 +7,10 @@ > namespace uc = std::__unicode; > using namespace std::string_view_literals; > > +static_assert( std::ranges::view<uc::_Utf8_view<std::string_view>> ); > +static_assert( std::ranges::view<uc::_Utf16_view<std::string_view>> ); > +static_assert( std::ranges::view<uc::_Utf32_view<std::string_view>> ); > + > template<std::ranges::range View> > constexpr void > compare(View v, std::basic_string_view<std::ranges::range_value_t<View>> > s) > @@ -87,18 +91,18 @@ test_illformed_utf16() > compare(uc::_Utf16_view(s.substr(0, 1)), r); > compare(uc::_Utf16_view(s.substr(1, 1)), r); > std::array s2{ s[0], s[0] }; > - compare(uc::_Utf16_view(s2), u"\uFFFD\uFFFD"sv); > + compare(uc::_Utf16_view(std::span(s2)), u"\uFFFD\uFFFD"sv); > std::array s3{ s[0], s[0], s[1] }; > - compare(uc::_Utf16_view(s3), u"\uFFFD\N{CLOWN FACE}"sv); > + compare(uc::_Utf16_view(std::span(s3)), u"\uFFFD\N{CLOWN FACE}"sv); > std::array s4{ s[1], s[0] }; > - compare(uc::_Utf16_view(s4), u"\uFFFD\uFFFD"sv); > + compare(uc::_Utf16_view(std::span(s4)), u"\uFFFD\uFFFD"sv); > std::array s5{ s[1], s[0], s[1] }; > - compare(uc::_Utf16_view(s5), u"\uFFFD\N{CLOWN FACE}"sv); > + compare(uc::_Utf16_view(std::span(s5)), u"\uFFFD\N{CLOWN FACE}"sv); > > std::array<char16_t, 2> s6{ 0xDC00, 0xDC01 }; > - compare(uc::_Utf16_view(s6), u"\uFFFD\uFFFD"sv); > + compare(uc::_Utf16_view(std::span(s6)), u"\uFFFD\uFFFD"sv); > std::array<char16_t, 2> s7{ 0xD7FF, 0xDC00 }; > - compare(uc::_Utf16_view(s7), u"\uD7FF\uFFFD"sv); > + compare(uc::_Utf16_view(std::span(s7)), u"\uD7FF\uFFFD"sv); > } > > constexpr void > -- > 2.51.0 > >
