Re: [PATCH] libstdc++: missing constexpr for __[nm]iter_base [PR102358]

[Jonathan Wakely <jwakely@redhat.com>]

On Thu, 21 Oct 2021 at 15:38, Patrick Palka via Libstdc++ <
libstdc++@gcc.gnu.org> wrote:

> Tested on x86_64-pc-linux-gnu, does this look ok for trunk/11/10?
>

Yes to all, thanks.



>         PR libstdc++/102358
>
> libstdc++-v3/ChangeLog:
>
>         * include/bits/stl_iterator.h (__niter_base): Make constexpr
>         for C++20.
>         (__miter_base): Likewise.
>         * testsuite/25_algorithms/move/constexpr.cc: New test.
> ---
>  libstdc++-v3/include/bits/stl_iterator.h      |  2 ++
>  .../testsuite/25_algorithms/move/constexpr.cc | 19 +++++++++++++++++++
>  2 files changed, 21 insertions(+)
>  create mode 100644 libstdc++-v3/testsuite/25_algorithms/move/constexpr.cc
>
> diff --git a/libstdc++-v3/include/bits/stl_iterator.h
> b/libstdc++-v3/include/bits/stl_iterator.h
> index 8afd6756613..fbd91956ced 100644
> --- a/libstdc++-v3/include/bits/stl_iterator.h
> +++ b/libstdc++-v3/include/bits/stl_iterator.h
> @@ -2470,6 +2470,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    /// @} group iterators
>
>    template<typename _Iterator>
> +    _GLIBCXX20_CONSTEXPR
>      auto
>      __niter_base(move_iterator<_Iterator> __it)
>      -> decltype(make_move_iterator(__niter_base(__it.base())))
> @@ -2483,6 +2484,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      };
>
>    template<typename _Iterator>
> +    _GLIBCXX20_CONSTEXPR
>      auto
>      __miter_base(move_iterator<_Iterator> __it)
>      -> decltype(__miter_base(__it.base()))
> diff --git a/libstdc++-v3/testsuite/25_algorithms/move/constexpr.cc
> b/libstdc++-v3/testsuite/25_algorithms/move/constexpr.cc
> new file mode 100644
> index 00000000000..773c55cfb50
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/25_algorithms/move/constexpr.cc
> @@ -0,0 +1,19 @@
> +// { dg-options "-std=gnu++20" }
> +// { dg-do compile { target c++20 } }
> +
> +#include <algorithm>
> +#include <span>
> +
> +constexpr bool
> +test01()
> +{
> +  // PR libstdc++/102358
> +  int x[2] = {1,2}, y[2];
> +  std::span in(x), out(y);
> +  std::move(std::move_iterator(in.begin()), std::move_iterator(in.end()),
> +           out.begin());
> +  return std::equal(std::move_iterator(in.begin()),
> std::move_iterator(in.end()),
> +                   std::move_iterator(out.begin()));
> +}
> +
> +static_assert(test01());
> --
> 2.33.1.711.g9d530dc002
>
>