On Fri, Oct 2, 2026 at 11:38 AM Jonathan Wakely <[email protected]> wrote:
> Add the missing partial specialization, and test for it.
>
> Also add tests for the as_const_view and as_rvalue_view partial
> specializations that weren't being tested.
>
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/125785
> * include/std/ranges (enable_borrowed_range<as_input_view<T>>):
> Define partial specialization.
> * testsuite/std/ranges/adaptors/as_input/1.cc: Test
> specialization for as_input_view.
> * testsuite/std/ranges/adaptors/as_const/1.cc: Test
> specialization for as_const_view.
> * testsuite/std/ranges/adaptors/as_rvalue/1.cc: Test
> specialization for as_rvalue_view.
> ---
>
> v2: Replace __gnu_test ranges with span and single_view as suggested by
> Tomasz.
>
This also LGTM.
>
> Tested x86_64-linux.
>
> libstdc++-v3/include/std/ranges | 4 ++++
> libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc | 5 +++++
> libstdc++-v3/testsuite/std/ranges/adaptors/as_input/1.cc | 6 ++++++
> libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc | 6 ++++++
> 4 files changed, 21 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/ranges
> b/libstdc++-v3/include/std/ranges
> index dde4ed90080d..37f048e3d0d3 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -10581,6 +10581,10 @@ namespace ranges
> template<typename _Range>
> as_input_view(_Range&&) -> as_input_view<views::all_t<_Range>>;
>
> + template<typename _Vp>
> + inline constexpr bool enable_borrowed_range<as_input_view<_Vp>>
> + = enable_borrowed_range<_Vp>;
> +
> template<input_range _Vp>
> requires view<_Vp>
> template<bool _Const>
> diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc
> b/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc
> index 5ccf47d4d300..135cc2911e93 100644
> --- a/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/as_const/1.cc
> @@ -81,6 +81,11 @@ test04()
> VERIFY( ranges::equal(v, x) );
> }
>
> +using Owning = ranges::single_view<int>;
> +using Borrowed = std::span<int>;
> +static_assert( !
> ranges::enable_borrowed_range<ranges::as_const_view<Owning>> );
> +static_assert(
> ranges::enable_borrowed_range<ranges::as_const_view<Borrowed>> );
> +
> int
> main()
> {
> diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/as_input/1.cc
> b/libstdc++-v3/testsuite/std/ranges/adaptors/as_input/1.cc
> index 8bd1a82a7b7f..2d2b2dd15821 100644
> --- a/libstdc++-v3/testsuite/std/ranges/adaptors/as_input/1.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/as_input/1.cc
> @@ -8,6 +8,7 @@
>
> #include <algorithm>
> #include <vector>
> +#include <span>
> #include <testsuite_hooks.h>
> #include <testsuite_iterators.h>
>
> @@ -51,6 +52,11 @@ test02()
> decltype(x | views::as_input |
> views::as_input)> );
> }
>
> +using Owning = ranges::single_view<int>;
> +using Borrowed = std::span<int>;
> +static_assert( !
> ranges::enable_borrowed_range<ranges::as_input_view<Owning>> );
> +static_assert(
> ranges::enable_borrowed_range<ranges::as_input_view<Borrowed>> );
> +
> int
> main()
> {
> diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc
> b/libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc
> index 487700773705..531560ad84af 100644
> --- a/libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc
> @@ -9,6 +9,7 @@
>
> #include <algorithm>
> #include <memory>
> +#include <span>
> #include <testsuite_hooks.h>
> #include <testsuite_iterators.h>
>
> @@ -55,6 +56,11 @@ test02()
> VERIFY( *y == 42 );
> }
>
> +using Owning = ranges::single_view<int>;
> +using Borrowed = std::span<int>;
> +static_assert( !
> ranges::enable_borrowed_range<ranges::as_rvalue_view<Owning>> );
> +static_assert(
> ranges::enable_borrowed_range<ranges::as_rvalue_view<Borrowed>> );
> +
> int
> main()
> {
> --
> 2.55.0
>
>
