On Wed, 17 Jan 2024, Jonathan Wakely wrote:
>
>
> On Wed, 17 Jan 2024, 02:37 Patrick Palka, <ppa...@redhat.com> wrote:
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
>
>
> OK
Thanks a lot. For the record I ended up not pushing this patch because
all the range adaptors it touches are C++23 ones and so ...
>
>
>
> -- >8 --
>
> This compile-time and diagnostic improvement[1] is less important in
> C++23 mode where deducing this is available and used in _Pipe, but for
> benefit of C++20 mode
... this isn't true. There's no real benefit in setting this flag for
standard C++23 range adaptors (besides consistency I guess, but OTOH not
setting it means more testing coverage for the deducing this code path).
> and for consistency let's set the flag on the most
> recently added range adaptors which lack it.
>
> [1]: Defining _S_has_simple_call_op=true for a range adaptor closure
> object signals that the adaptor has an operator() that's not overloaded
> according to the constness/value category of the object, which in turn
> allows us to implement the operator() of the composition of such
> adaptors
> in a simpler way.
>
> libstdc++-v3/ChangeLog:
>
> * include/std/ranges (views::_Adjacent::_S_has_simple_call_op):
> Define to true.
> (views::_AsRvalue::_S_has_simple_call_op): Likewise.
> (views::_Enumerate::_S_has_simple_call_op): Likewise.
> (views::_AsConst::_S_has_simple_call_op): Likewise.
> ---
> libstdc++-v3/include/std/ranges | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/ranges
> b/libstdc++-v3/include/std/ranges
> index 7ef835f486a..66502cc1da4 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -5669,6 +5669,8 @@ namespace views::__adaptor
> else
> return adjacent_view<all_t<_Range>,
> _Nm>(std::forward<_Range>(__r));
> }
> +
> + static constexpr bool _S_has_simple_call_op = true;
> };
>
> template<size_t _Nm>
> @@ -8844,6 +8846,8 @@ namespace views::__adaptor
> else
> return as_rvalue_view(std::forward<_Range>(__r));
> }
> +
> + static constexpr bool _S_has_simple_call_op = true;
> };
>
> inline constexpr _AsRvalue as_rvalue;
> @@ -9147,6 +9151,8 @@ namespace views::__adaptor
> constexpr auto
> operator() [[nodiscard]] (_Range&& __r) const
> { return
> enumerate_view<all_t<_Range>>(std::forward<_Range>(__r)); }
> +
> + static constexpr bool _S_has_simple_call_op = true;
> };
>
> inline constexpr _Enumerate enumerate;
> @@ -9253,6 +9259,8 @@ namespace views::__adaptor
> else
> return as_const_view(std::forward<_Range>(__r));
> }
> +
> + static constexpr bool _S_has_simple_call_op = true;
> };
>
> inline constexpr _AsConst as_const;
> --
> 2.43.0.367.g186b115d30
>
>
>
