From: Patrick Palka <ppalka@redhat.com>
To: Patrick Palka <ppalka@redhat.com>
Cc: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org, jwakely@redhat.com
Subject: Re: [PATCH] libstdc++: Add missing bits of P0896R4 pertaining to [back|front]_insert_iterator
Date: Mon, 24 Feb 2020 13:37:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.22.395.2002240830390.1709@idea> (raw)
In-Reply-To: <20200224132934.559186-1-ppalka@redhat.com>
ZOn Mon, 24 Feb 2020, Patrick Palka wrote:
> This adds some missing pieces of the Ranges TS that make back_insert_iterator and
> front_insert_iterator conform to the new output_iterator requirements.
>
> It also fixes a bug in ranges::__copy_or_move and
> ranges::__copy_or_move_backward in which we were inspecting the iter_value_t of
> the output iterator, but iterators such as back_insert_iterator and
> front_insert_iterator whose value_type is defined to be void do not have an
> iter_value_t according to [readable.traits] p4. The entire __use_memmove
> condition can probably be refactored, but the simplest fix for now is to inspect
> the iterator_traits of the output iterator instead.
>
> libstdc++-v3/ChangeLog:
>
> PR libstdc++/93884
> * include/bits/ranges_algobase.h (__copy_or_move,
> __copy_or_move_backward): Don't inspect the iter_value_t of the output
> iterator, instead inspect its iterator_traits directly.
> * include/bits/stl_iterator.h (back_insert_iterator::container):
> Conditionally initialize.
> (back_insert_iterator::difference_type): Conditionally define.
> (back_insert_iterator::back_insert_iterator): Conditionally define this
> default constructor.
> (front_insert_iterator::container): Conditionally initialize.
> (front_insert_iterator::difference_type): Conditionally define.
> (front_insert_iterator::front_insert_iterator): Conditionally define
> this default constructor.
> ---
> libstdc++-v3/include/bits/ranges_algobase.h | 4 +-
> libstdc++-v3/include/bits/stl_iterator.h | 22 ++++++++++
> .../back_insert_iterator/pr93884.C | 44 +++++++++++++++++++
> .../front_insert_iterator/pr93884.C | 44 +++++++++++++++++++
> 4 files changed, 112 insertions(+), 2 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/24_iterators/back_insert_iterator/pr93884.C
> create mode 100644 libstdc++-v3/testsuite/24_iterators/front_insert_iterator/pr93884.C
>
> diff --git a/libstdc++-v3/include/bits/ranges_algobase.h b/libstdc++-v3/include/bits/ranges_algobase.h
> index 807822e99c8..739424e1a2d 100644
> --- a/libstdc++-v3/include/bits/ranges_algobase.h
> +++ b/libstdc++-v3/include/bits/ranges_algobase.h
> @@ -249,7 +249,7 @@ namespace ranges
> else if constexpr (sized_sentinel_for<_Sent, _Iter>)
> {
> using _ValueTypeI = iter_value_t<_Iter>;
> - using _ValueTypeO = iter_value_t<_Out>;
> + using _ValueTypeO = iterator_traits<_Out>::value_type;
> constexpr bool __use_memmove
> = (is_trivially_copyable_v<_ValueTypeI>
> && is_same_v<_ValueTypeI, _ValueTypeO>
> @@ -386,7 +386,7 @@ namespace ranges
> else if constexpr (sized_sentinel_for<_Sent, _Iter>)
> {
> using _ValueTypeI = iter_value_t<_Iter>;
> - using _ValueTypeO = iter_value_t<_Out>;
> + using _ValueTypeO = iterator_traits<_Out>::value_type;
> constexpr bool __use_memmove
> = (is_trivially_copyable_v<_ValueTypeI>
> && is_same_v<_ValueTypeI, _ValueTypeO>
> diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h
> index 372df223113..0f2742ae4cf 100644
> --- a/libstdc++-v3/include/bits/stl_iterator.h
> +++ b/libstdc++-v3/include/bits/stl_iterator.h
> @@ -496,11 +496,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> : public iterator<output_iterator_tag, void, void, void, void>
> {
> protected:
> +#if __cplusplus > 201703L
> + _Container* container = nullptr;
> +#else
> _Container* container;
> +#endif
Just noticed the order of this conditional is inconsistent with ...
>
> public:
> /// A nested typedef for the type of whatever container you used.
> typedef _Container container_type;
> +#if __cplusplus > 201703L
> + using difference_type = ptrdiff_t;
> +#endif
> +
> +#if __cplusplus > 201703L
> + constexpr back_insert_iterator() noexcept = default;
> +#endif
>
> /// The only way to create this %iterator is with a container.
> explicit
> @@ -588,11 +599,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> : public iterator<output_iterator_tag, void, void, void, void>
> {
> protected:
> +#if __cplusplus <= 201703L
> _Container* container;
> +#else
> + _Container* container = nullptr;
> +#endif
... this one. Consider this fixed so that both conditionals are
__cplusplus <= 201703L, specifying the pre-C++20 version of the code
first.
next prev parent reply other threads:[~2020-02-24 13:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-24 13:29 Patrick Palka
2020-02-24 13:37 ` Patrick Palka [this message]
2020-02-24 13:43 ` Jonathan Wakely
2020-02-24 13:53 ` Patrick Palka
2020-02-24 14:25 ` Jonathan Wakely
2020-02-24 17:17 ` Jonathan Wakely
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