Re: [PATCH 2/2] libstdc++: Implement range_adaptor_closure from P2387R3 [PR108827]

[Jonathan Wakely <jwakely.gcc@gmail.com>]

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On Mon, 17 Apr 2023, 05:28 Patrick Palka via Libstdc++, <
libstdc++@gcc.gnu.org> wrote:

> On Fri, 14 Apr 2023, Patrick Palka wrote:
>
> > Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
> >
> >       PR libstdc++/108827
> >
> > libstdc++-v3/ChangeLog:
> >
> >       * include/bits/ranges_cmp.h (__cpp_lib_ranges): Bump value
> >       for C++23.
> >       * include/std/ranges (range_adaptor_closure): Define for C++23.
> >       * include/std/version (__cpp_lib_ranges): Bump value for
> >       C++23.
> >       * testsuite/std/ranges/version_c++23.cc: Bump expected value
> >       of __cpp_lib_ranges.
> >       * testsuite/std/ranges/range_adaptor_closure.cc: New test.
>
> Here's a standalone version of this patch (not dependent on the first
> patch in the series) it terms of the current non-CRTP representation
> of _RangeAdaptorClosure:
>

OK, thanks for separating this from the other change.



> -- >8 --
>
> Subject: [PATCH] libstdc++: Implement range_adaptor_closure from P2387R3
>  [PR108827]
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
>
>         PR libstdc++/108827
>
> libstdc++-v3/ChangeLog:
>
>         * include/bits/ranges_cmp.h (__cpp_lib_ranges): Bump value
>         for C++23.
>         * include/std/ranges (range_adaptor_closure): Define for C++23.
>         * include/std/version (__cpp_lib_ranges): Bump value for
>         C++23.
>         * testsuite/std/ranges/version_c++23.cc: Bump expected value
>         of __cpp_lib_ranges.
>         * testsuite/std/ranges/range_adaptor_closure.cc: New test.
> ---
>  libstdc++-v3/include/bits/ranges_cmp.h        |  4 ++
>  libstdc++-v3/include/std/ranges               |  8 ++++
>  libstdc++-v3/include/std/version              |  3 ++
>  .../std/ranges/range_adaptor_closure.cc       | 46 +++++++++++++++++++
>  .../testsuite/std/ranges/version_c++23.cc     |  2 +-
>  5 files changed, 62 insertions(+), 1 deletion(-)
>  create mode 100644
> libstdc++-v3/testsuite/std/ranges/range_adaptor_closure.cc
>
> diff --git a/libstdc++-v3/include/bits/ranges_cmp.h
> b/libstdc++-v3/include/bits/ranges_cmp.h
> index 85c1a77ccf7..6710d829a37 100644
> --- a/libstdc++-v3/include/bits/ranges_cmp.h
> +++ b/libstdc++-v3/include/bits/ranges_cmp.h
> @@ -57,7 +57,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
>  #ifdef __cpp_lib_concepts
>  // Define this here, included by all the headers that need to define it.
> +#if __cplusplus > 202002L
> +#define __cpp_lib_ranges 202202L
> +#else
>  #define __cpp_lib_ranges 202110L
> +#endif
>
>  namespace ranges
>  {
> diff --git a/libstdc++-v3/include/std/ranges
> b/libstdc++-v3/include/std/ranges
> index 1714f3fb16c..c4d4d85bf90 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -1122,6 +1122,14 @@ namespace views::__adaptor
>      };
>  } // namespace views::__adaptor
>
> +#if __cplusplus > 202002L
> +  template<typename _Derived>
> +    requires is_class_v<_Derived> && same_as<_Derived,
> remove_cv_t<_Derived>>
> +    class range_adaptor_closure
> +    : public views::__adaptor::_RangeAdaptorClosure
> +    { };
> +#endif
> +
>    template<range _Range> requires is_object_v<_Range>
>      class ref_view : public view_interface<ref_view<_Range>>
>      {
> diff --git a/libstdc++-v3/include/std/version
> b/libstdc++-v3/include/std/version
> index 027e5711ec5..02ead8f1443 100644
> --- a/libstdc++-v3/include/std/version
> +++ b/libstdc++-v3/include/std/version
> @@ -265,8 +265,10 @@
>  #define __cpp_lib_interpolate 201902L
>  #if __cpp_lib_concepts
>  # define __cpp_lib_move_iterator_concept 202207L
> +#if __cplusplus <= 202002L // N.B. updated value in C++23
>  # define __cpp_lib_ranges 202110L
>  #endif
> +#endif
>  #define __cpp_lib_shift 201806L
>
>  #if _GLIBCXX_HOSTED
> @@ -330,6 +332,7 @@
>  #define __cpp_lib_reference_from_temporary 202202L
>  #define __cpp_lib_to_underlying 202102L
>  #define __cpp_lib_unreachable 202202L
> +#define __cpp_lib_ranges 202202L
>  #define __cpp_lib_ranges_zip 202110L
>  #define __cpp_lib_ranges_chunk 202202L
>  #define __cpp_lib_ranges_slide 202202L
> diff --git a/libstdc++-v3/testsuite/std/ranges/range_adaptor_closure.cc
> b/libstdc++-v3/testsuite/std/ranges/range_adaptor_closure.cc
> new file mode 100644
> index 00000000000..6221f071331
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/std/ranges/range_adaptor_closure.cc
> @@ -0,0 +1,46 @@
> +// { dg-options "-std=gnu++23" }
> +// { dg-do run { target c++23 } }
> +
> +#include <ranges>
> +#include <algorithm>
> +#include <testsuite_hooks.h>
> +
> +namespace ranges = std::ranges;
> +namespace views = std::views;
> +
> +struct _Negate : ranges::range_adaptor_closure<_Negate>
> +{
> +  template<ranges::viewable_range _Range>
> +  constexpr auto
> +  operator()(_Range&& __r) const
> +  requires requires { views::transform(std::declval<_Range>(),
> std::negate{}); }
> +  { return views::transform(std::forward<_Range>(__r), std::negate{}); }
> +};
> +
> +constexpr _Negate negate;
> +
> +constexpr bool
> +test01()
> +{
> +  int x[] = {1, 2, 3};
> +  VERIFY( ranges::equal(x | negate, (int[]){-1, -2, -3}) );
> +  VERIFY( ranges::equal(x | negate | negate, x) );
> +  VERIFY( ranges::equal(x | (negate | negate), x) );
> +  VERIFY( ranges::equal(x | views::reverse | negate, x | negate |
> views::reverse) );
> +  VERIFY( ranges::equal(x | (views::reverse | negate), x | (negate |
> views::reverse)) );
> +#if 0
> +  // These asserts currently fail for the same reason as the disabled
> asserts
> +  // in std/ranges/adaptors/all.cc.
> +  static_assert( sizeof(negate | views::reverse | views::join) == 1 );
> +  static_assert( sizeof(views::reverse | negate | views::join) == 1 );
> +  static_assert( sizeof(views::reverse | views::join | negate) == 1 );
> +#endif
> +
> +  return true;
> +}
> +
> +int
> +main()
> +{
> +  static_assert(test01());
> +}
> diff --git a/libstdc++-v3/testsuite/std/ranges/version_c++23.cc
> b/libstdc++-v3/testsuite/std/ranges/version_c++23.cc
> index 04609bb602c..e8342fa986a 100644
> --- a/libstdc++-v3/testsuite/std/ranges/version_c++23.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/version_c++23.cc
> @@ -4,7 +4,7 @@
>  #include <version>
>
>  #if __STDC_HOSTED__
> -# if __cpp_lib_ranges != 202110L
> +# if __cpp_lib_ranges != 202202L
>  #  error "Feature-test macro __cpp_lib_ranges has wrong value in
> <version>"
>  # endif
>  #endif
> --
> 2.40.0.335.g9857273be0
>
>