Re: [PATCH v3] libstdc++: Fix std::ranges::iota not in numeric [PR108760]

[Jonathan Wakely <jwakely@redhat.com>]

On Thu, 6 Jun 2024 at 21:49, Michael Levine (BLOOMBERG/ 731 LEX)
<mlevine55@bloomberg.net> wrote:
>
> To test the theory that this issue was unrelated to my patch, I moved the out_value_result definition into std/numeric and restored the version of bits/ranges_algobase.h to the version in master. I kept the include line "include <bits/ranges_algobase.h>" in std/numeric even though it wasn't being used. With the include line I see the same error about __memcmp is not a member of 'std'.

Thanks, I'll fix that separately and then apply your patch for iota.


>
> From: Michael Levine (BLOOMBERG/ 731 LEX) At: 05/30/24 13:43:58 UTC-4:00
> To: jwakely@redhat.com
> Cc: ppalka@redhat.com, gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org
> Subject: Re: [PATCH v3] libstdc++: Fix std::ranges::iota not in numeric [PR108760]
>
> When I remove <bits/stl_algobase.h> for importing __memcmp (my apologies for writing __memcpy) from libstdc++-v3/include/bits/ranges_algobase.h and try to rerun the code, I get the following error:
>
> In file included from $HOME/projects/objdirforgcc/_pfx/include/c++/15.0.0/numeric:69,
> from ranges-iota-fix.cpp:1:
> $HOME/projects/objdirforgcc/_pfx/include/c++/15.0.0/bits/ranges_algobase.h: In member function ‘constexpr bool std::ranges::__equal_fn::operator()(_Iter1, _Sent1, _Iter2, _Sent2, _Pred, _Proj1, _Proj2) const’:
> $HOME/projects/objdirforgcc/_pfx/include/c++/15.0.0/bits/ranges_algobase.h:143:32: error: ‘__memcmp’ is not a member of ‘std’; did you mean ‘__memcmpable’?
> 143 | return !std::__memcmp(__first1, __first2, __len);
> | ^~~~~~~~
> | __memcmpable
>
> From: jwakely@redhat.com At: 05/24/24 10:12:57 UTC-4:00
> To: Michael Levine (BLOOMBERG/ 731 LEX )
> Cc: ppalka@redhat.com, gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org
> Subject: Re: [PATCH v3] libstdc++: Fix std::ranges::iota not in numeric [PR108760]
>
> On 24/05/24 13:56 -0000, Michael Levine (BLOOMBERG/ 731 LEX) wrote:
> >I've attached the v3 version of the patch as a single, squashed patch
> containing all of the changes. I manually prepended my sign off to the patch.
>
>
> >Signed-off-by: Michael Levine <mlevine55@bloomberg.net>
> >---
> >diff --git a/libstdc++-v3/include/bits/ranges_algo.h
> b/libstdc++-v3/include/bits/ranges_algo.h
> >index 62faff173bd..d258be0b93f 100644
> >--- a/libstdc++-v3/include/bits/ranges_algo.h
> >+++ b/libstdc++-v3/include/bits/ranges_algo.h
> >@@ -3521,58 +3521,6 @@ namespace ranges
> >
> > #endif // __glibcxx_ranges_contains
> >
> >-#if __glibcxx_ranges_iota >= 202202L // C++ >= 23
> >-
> >- template<typename _Out, typename _Tp>
> >- struct out_value_result
> >- {
> >- [[no_unique_address]] _Out out;
> >- [[no_unique_address]] _Tp value;
> >-
> >- template<typename _Out2, typename _Tp2>
> >- requires convertible_to<const _Out&, _Out2>
> >- && convertible_to<const _Tp&, _Tp2>
> >- constexpr
> >- operator out_value_result<_Out2, _Tp2>() const &
> >- { return {out, value}; }
> >-
> >- template<typename _Out2, typename _Tp2>
> >- requires convertible_to<_Out, _Out2>
> >- && convertible_to<_Tp, _Tp2>
> >- constexpr
> >- operator out_value_result<_Out2, _Tp2>() &&
> >- { return {std::move(out), std::move(value)}; }
> >- };
> >-
> >- template<typename _Out, typename _Tp>
> >- using iota_result = out_value_result<_Out, _Tp>;
> >-
> >- struct __iota_fn
> >- {
> >- template<input_or_output_iterator _Out, sentinel_for<_Out> _Sent,
> weakly_incrementable _Tp>
> >- requires indirectly_writable<_Out, const _Tp&>
> >- constexpr iota_result<_Out, _Tp>
> >- operator()(_Out __first, _Sent __last, _Tp __value) const
> >- {
> >- while (__first != __last)
> >- {
> >- *__first = static_cast<const _Tp&>(__value);
> >- ++__first;
> >- ++__value;
> >- }
> >- return {std::move(__first), std::move(__value)};
> >- }
> >-
> >- template<weakly_incrementable _Tp, output_range<const _Tp&> _Range>
> >- constexpr iota_result<borrowed_iterator_t<_Range>, _Tp>
> >- operator()(_Range&& __r, _Tp __value) const
> >- { return (*this)(ranges::begin(__r), ranges::end(__r),
> std::move(__value)); }
> >- };
> >-
> >- inline constexpr __iota_fn iota{};
> >-
> >-#endif // __glibcxx_ranges_iota
> >-
> > #if __glibcxx_ranges_find_last >= 202207L // C++ >= 23
> >
> > struct __find_last_fn
> >diff --git a/libstdc++-v3/include/bits/ranges_algobase.h
> b/libstdc++-v3/include/bits/ranges_algobase.h
> >index e26a73a27d6..965b36aed35 100644
> >--- a/libstdc++-v3/include/bits/ranges_algobase.h
> >+++ b/libstdc++-v3/include/bits/ranges_algobase.h
> >@@ -35,6 +35,7 @@
> > #include <compare>
> > #include <bits/stl_iterator_base_funcs.h>
> > #include <bits/stl_iterator.h>
> >+#include <bits/stl_algobase.h> // __memcpy
>
> Why is this being added here? What is __memcpy?
>
> I don't think out_value_result requires any new headers to be included
> here, does it?
>
> > #include <bits/ranges_base.h> // ranges::begin, ranges::range etc.
> > #include <bits/invoke.h> // __invoke
> > #include <bits/cpp_type_traits.h> // __is_byte
> >@@ -70,6 +71,32 @@ namespace ranges
> > __is_move_iterator<move_iterator<_Iterator>> = true;
> > } // namespace __detail
> >
> >+#if __glibcxx_ranges_iota >= 202202L // C++ >= 23
> >+
> >+ template<typename _Out, typename _Tp>
> >+ struct out_value_result
> >+ {
> >+ [[no_unique_address]] _Out out;
> >+ [[no_unique_address]] _Tp value;
> >+
> >+ template<typename _Out2, typename _Tp2>
> >+ requires convertible_to<const _Out&, _Out2>
> >+ && convertible_to<const _Tp&, _Tp2>
> >+ constexpr
> >+ operator out_value_result<_Out2, _Tp2>() const &
> >+ { return {out, value}; }
> >+
> >+ template<typename _Out2, typename _Tp2>
> >+ requires convertible_to<_Out, _Out2>
> >+ && convertible_to<_Tp, _Tp2>
> >+ constexpr
> >+ operator out_value_result<_Out2, _Tp2>() &&
> >+ { return {std::move(out), std::move(value)}; }
> >+ };
> >+
> >+#endif // __glibcxx_ranges_iota
> >+
> >+
> > struct __equal_fn
> > {
> > template<input_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
> >diff --git a/libstdc++-v3/include/std/numeric
> b/libstdc++-v3/include/std/numeric
> >index c912db4a519..d88f7f02137 100644
> >--- a/libstdc++-v3/include/std/numeric
> >+++ b/libstdc++-v3/include/std/numeric
> >@@ -65,6 +65,10 @@
> > # include <parallel/numeric>
> > #endif
> >
> >+#if __glibcxx_ranges_iota >= 202202L // C++ >= 23
> >+#include <bits/ranges_algobase.h> // for out_value_result as used by
> std::ranges::iota. It transitively also brings in <bits/ranges_base.h>, from
> which _Range is used by std::ranges::iota
>
> We generally try to keep lines below 80 columns, or 120 at a push.
> This is unnecessarily long, and I don't know what _Range is meant to
> be (that's just a template parameter, not something defined in
> <bits/ranges_algobase.h>. Please just use:
>
> #include <bits/ranges_algobase.h> // for ranges::out_value_result
>
> Otherwise this looks ready to go in, thanks.
>
> >+#endif // __glibcxx_ranges_iota
> >+
> > #if __cplusplus >= 201402L
> > # include <type_traits>
> > # include <bit>
> >@@ -726,6 +730,40 @@ namespace __detail
> > /// @} group numeric_ops
> > #endif // C++17
> >
> >+namespace ranges
> >+{
> >+#if __glibcxx_ranges_iota >= 202202L // C++ >= 23
> >+
> >+ template<typename _Out, typename _Tp>
> >+ using iota_result = out_value_result<_Out, _Tp>;
> >+
> >+ struct __iota_fn
> >+ {
> >+ template<input_or_output_iterator _Out, sentinel_for<_Out> _Sent,
> weakly_incrementable _Tp>
> >+ requires indirectly_writable<_Out, const _Tp&>
> >+ constexpr iota_result<_Out, _Tp>
> >+ operator()(_Out __first, _Sent __last, _Tp __value) const
> >+ {
> >+ while (__first != __last)
> >+ {
> >+ *__first = static_cast<const _Tp&>(__value);
> >+ ++__first;
> >+ ++__value;
> >+ }
> >+ return {std::move(__first), std::move(__value)};
> >+ }
> >+
> >+ template<weakly_incrementable _Tp, output_range<const _Tp&> _Range>
> >+ constexpr iota_result<borrowed_iterator_t<_Range>, _Tp>
> >+ operator()(_Range&& __r, _Tp __value) const
> >+ { return (*this)(ranges::begin(__r), ranges::end(__r),
> std::move(__value)); }
> >+ };
> >+
> >+ inline constexpr __iota_fn iota{};
> >+
> >+#endif // __glibcxx_ranges_iota
> >+} // namespace ranges
> >+
> > _GLIBCXX_END_NAMESPACE_VERSION
> > } // namespace std
> >
> >diff --git a/libstdc++-v3/testsuite/25_algorithms/iota/1.cc
> b/libstdc++-v3/testsuite/26_numerics/iota/2.cc
> >similarity index 96%
> >rename from libstdc++-v3/testsuite/25_algorithms/iota/1.cc
> >rename to libstdc++-v3/testsuite/26_numerics/iota/2.cc
> >index 61bf418b4da..040c48d91ce 100644
> >--- a/libstdc++-v3/testsuite/25_algorithms/iota/1.cc
> >+++ b/libstdc++-v3/testsuite/26_numerics/iota/2.cc
> >@@ -1,6 +1,6 @@
> > // { dg-do run { target c++23 } }
> >
> >-#include <algorithm>
> >+#include <numeric>
> > #include <testsuite_hooks.h>
> > #include <testsuite_iterators.h>
> >
>
>