On Thu, Jun 12, 2025 at 7:33 PM Patrick Palka <ppa...@redhat.com> wrote:
> On Thu, 12 Jun 2025, Patrick Palka wrote:
>
> > Changes in v4:
> > * Don't pass a projection function throughout the helpers, instead
> > create a pass a composite predicate via __make_comp_proj.
>
LGTM.
> >
> > -- >8 --
> >
> > As with the previous patch, this patch reimplements ranges::sort
> > directly instead of incorrectly forwarding to std::sort. In addition to
> > the compatibility changes listed in the previous patch we also:
> >
> > - use ranges::iter_swap instead of std::iter_swap
> > - use ranges::move_backward instead of std::move_backward
> > - use __bit_width and __to_unsigned_like instead of __lg
> >
> > PR libstdc++/100795
> > PR libstdc++/118209
> >
> > libstdc++-v3/ChangeLog:
> >
> > * include/bits/max_size_type.h (__bit_width): New explicit
> > specialization for __max_size_type.
> > * include/bits/ranges_algo.h (__detail::__move_median_to_first):
> > New, based on the stl_algo.h implementation.
> > (__detail::__unguarded_liner_insert): Likewise.
> > (__detail::__insertion_sort): Likewise.
> > (__detail::__sort_threshold): Likewise.
> > (__detail::__unguarded_insertion_sort): Likewise.
> > (__detail::__final_insertion_sort): Likewise.
> > (__detail::__unguarded_partition): Likewise.
> > (__detail::__unguarded_partition_pivot): Likewise.
> > (__detail::__heap_select): Likewise.
> > (__detail::__partial_sort): Likewise.
> > (__detail::__introsort_loop): Likewise.
> > (__sort_fn::operator()): Reimplement in terms of the above.
> > * libstdc++-v3/testsuite/25_algorithms/sort/118209.cc: New test.
> > * libstdc++-v3/testsuite/25_algorithms/sort/constrained.cc
> > (test03): New test.
> > ---
> > libstdc++-v3/include/bits/max_size_type.h | 11 ++
> > libstdc++-v3/include/bits/ranges_algo.h | 167 +++++++++++++++++-
> > .../testsuite/25_algorithms/sort/118209.cc | 23 +++
> > .../25_algorithms/sort/constrained.cc | 31 ++++
> > 4 files changed, 228 insertions(+), 4 deletions(-)
> > create mode 100644 libstdc++-v3/testsuite/25_algorithms/sort/118209.cc
> >
> > diff --git a/libstdc++-v3/include/bits/max_size_type.h
> b/libstdc++-v3/include/bits/max_size_type.h
> > index e602b1b4bee5..73a6d141d5bc 100644
> > --- a/libstdc++-v3/include/bits/max_size_type.h
> > +++ b/libstdc++-v3/include/bits/max_size_type.h
> > @@ -36,6 +36,7 @@
> >
> > #if __cplusplus > 201703L && __cpp_lib_concepts
> > #include <ext/numeric_traits.h>
> > +#include <bit> // __bit_width
> > #include <numbers>
> >
> > // This header implements unsigned and signed integer-class types (as
> per
> > @@ -818,6 +819,16 @@ namespace ranges
> > { return min(); }
> > };
> >
> > + template<>
> > + inline constexpr int
> > + __bit_width(ranges::__detail::__max_size_type __x) noexcept
> > + {
> > + if (__x._M_msb)
> > + return numeric_limits<ranges::__detail::__max_size_type>::digits;
> > + else
> > + return std::__bit_width(__x._M_val);
> > + }
> > +
> > _GLIBCXX_END_NAMESPACE_VERSION
> > } // namespace
> >
> > diff --git a/libstdc++-v3/include/bits/ranges_algo.h
> b/libstdc++-v3/include/bits/ranges_algo.h
> > index 4f10501956a7..9f94c6b1d57e 100644
> > --- a/libstdc++-v3/include/bits/ranges_algo.h
> > +++ b/libstdc++-v3/include/bits/ranges_algo.h
> > @@ -32,6 +32,7 @@
> >
> > #if __cplusplus > 201703L
> >
> > +#include <bit> // __bit_width
> > #if __cplusplus > 202002L
> > #include <optional>
> > #endif
> > @@ -2169,6 +2170,153 @@ namespace ranges
> >
> > inline constexpr __is_heap_fn is_heap{};
> >
> > + namespace __detail
> > + {
> > + template<typename _Iter, typename _Comp>
> > + constexpr void
> > + __move_median_to_first(_Iter __result, _Iter __a, _Iter __b,
> _Iter __c,
> > + _Comp __comp)
> > + {
> > + if (std::__invoke(__comp, *__a, *__b))
>
> Similarly, these __invoke calls throughout are unnecessary too.
> Fixed below.
>
> -- >8 --
>
> PR libstdc++/100795
> PR libstdc++/118209
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/max_size_type.h (__bit_width): New explicit
> specializatino for __max_size_type.
> * include/bits/ranges_algo.h (__detail::__move_median_to_first):
> New, based on the stl_algo.h implementation.
> (__detail::__unguarded_liner_insert): Likewise.
> (__detail::__insertion_sort): Likewise.
> (__detail::__sort_threshold): Likewise.
> (__detail::__unguarded_insertion_sort): Likewise.
> (__detail::__final_insertion_sort): Likewise.
> (__detail::__unguarded_partition): Likewise.
> (__detail::__unguarded_partition_pivot): Likewise.
> (__detail::__heap_select): Likewise.
> (__detail::__partial_sort): Likewise.
> (__detail::__introsort_loop): Likewise.
> (__sort_fn::operator()): Reimplement in terms of the above.
> * libstdc++-v3/testsuite/25_algorithms/sort/118209.cc: New test.
> * libstdc++-v3/testsuite/25_algorithms/sort/constrained.cc
> (test03): New test.
> ---
> libstdc++-v3/include/bits/max_size_type.h | 11 ++
> libstdc++-v3/include/bits/ranges_algo.h | 167 +++++++++++++++++-
> .../testsuite/25_algorithms/sort/118209.cc | 23 +++
> .../25_algorithms/sort/constrained.cc | 31 ++++
> 4 files changed, 228 insertions(+), 4 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/25_algorithms/sort/118209.cc
>
> diff --git a/libstdc++-v3/include/bits/max_size_type.h
> b/libstdc++-v3/include/bits/max_size_type.h
> index e602b1b4bee5..73a6d141d5bc 100644
> --- a/libstdc++-v3/include/bits/max_size_type.h
> +++ b/libstdc++-v3/include/bits/max_size_type.h
> @@ -36,6 +36,7 @@
>
> #if __cplusplus > 201703L && __cpp_lib_concepts
> #include <ext/numeric_traits.h>
> +#include <bit> // __bit_width
> #include <numbers>
>
> // This header implements unsigned and signed integer-class types (as per
> @@ -818,6 +819,16 @@ namespace ranges
> { return min(); }
> };
>
> + template<>
> + inline constexpr int
> + __bit_width(ranges::__detail::__max_size_type __x) noexcept
> + {
> + if (__x._M_msb)
> + return numeric_limits<ranges::__detail::__max_size_type>::digits;
> + else
> + return std::__bit_width(__x._M_val);
> + }
> +
> _GLIBCXX_END_NAMESPACE_VERSION
> } // namespace
>
> diff --git a/libstdc++-v3/include/bits/ranges_algo.h
> b/libstdc++-v3/include/bits/ranges_algo.h
> index 735142a6c702..cc182d110b30 100644
> --- a/libstdc++-v3/include/bits/ranges_algo.h
> +++ b/libstdc++-v3/include/bits/ranges_algo.h
> @@ -32,6 +32,7 @@
>
> #if __cplusplus > 201703L
>
> +#include <bit> // __bit_width
> #if __cplusplus > 202002L
> #include <optional>
> #endif
> @@ -2168,6 +2169,153 @@ namespace ranges
>
> inline constexpr __is_heap_fn is_heap{};
>
> + namespace __detail
> + {
> + template<typename _Iter, typename _Comp>
> + constexpr void
> + __move_median_to_first(_Iter __result, _Iter __a, _Iter __b, _Iter
> __c,
> + _Comp __comp)
> + {
> + if (__comp(*__a, *__b))
> + {
> + if (__comp(*__b, *__c))
> + ranges::iter_swap(__result, __b);
> + else if (__comp(*__a, *__c))
> + ranges::iter_swap(__result, __c);
> + else
> + ranges::iter_swap(__result, __a);
> + }
> + else if (__comp(*__a, *__c))
> + ranges::iter_swap(__result, __a);
> + else if (__comp(*__b, *__c))
> + ranges::iter_swap(__result, __c);
> + else
> + ranges::iter_swap(__result, __b);
> + }
> +
> + template<typename _Iter, typename _Comp>
> + constexpr void
> + __unguarded_linear_insert(_Iter __last, _Comp __comp)
> + {
> + iter_value_t<_Iter> __val = ranges::iter_move(__last);
> + _Iter __next = __last;
> + --__next;
> + while (__comp(__val, *__next))
> + {
> + *__last = ranges::iter_move(__next);
> + __last = __next;
> + --__next;
> + }
> + *__last = std::move(__val);
> + }
> +
> + template<typename _Iter, typename _Comp>
> + constexpr void
> + __insertion_sort(_Iter __first, _Iter __last, _Comp __comp)
> + {
> + if (__first == __last) return;
> +
> + for (_Iter __i = __first + 1; __i != __last; ++__i)
> + {
> + if (__comp(*__i, *__first))
> + {
> + iter_value_t<_Iter> __val = ranges::iter_move(__i);
> + ranges::move_backward(__first, __i, __i + 1);
> + *__first = std::move(__val);
> + }
> + else
> + __detail::__unguarded_linear_insert(__i, __comp);
> + }
> + }
> +
> + template<typename _Iter, typename _Comp>
> + constexpr void
> + __unguarded_insertion_sort(_Iter __first, _Iter __last, _Comp
> __comp)
> + {
> + for (_Iter __i = __first; __i != __last; ++__i)
> + __detail::__unguarded_linear_insert(__i, __comp);
> + }
> +
> + inline constexpr int __sort_threshold = 16;
> +
> + template<typename _Iter, typename _Comp>
> + constexpr void
> + __final_insertion_sort(_Iter __first, _Iter __last, _Comp __comp)
> + {
> + if (__last - __first > __sort_threshold)
> + {
> + __detail::__insertion_sort(__first, __first +
> __sort_threshold, __comp);
> + __detail::__unguarded_insertion_sort(__first +
> __sort_threshold, __last,
> + __comp);
> + }
> + else
> + __detail::__insertion_sort(__first, __last, __comp);
> + }
> +
> + template<typename _Iter, typename _Comp>
> + constexpr _Iter
> + __unguarded_partition(_Iter __first, _Iter __last, _Iter __pivot,
> _Comp __comp)
> + {
> + while (true)
> + {
> + while (__comp(*__first, *__pivot))
> + ++__first;
> + --__last;
> + while (__comp(*__pivot, *__last))
> + --__last;
> + if (!(__first < __last))
> + return __first;
> + ranges::iter_swap(__first, __last);
> + ++__first;
> + }
> + }
> +
> + template<typename _Iter, typename _Comp>
> + constexpr _Iter
> + __unguarded_partition_pivot(_Iter __first, _Iter __last, _Comp
> __comp)
> + {
> + _Iter __mid = __first + (__last - __first) / 2;
> + __detail::__move_median_to_first(__first, __first + 1, __mid,
> __last - 1, __comp);
> + return __detail::__unguarded_partition(__first + 1, __last,
> __first, __comp);
> + }
> +
> + template<typename _Iter, typename _Comp>
> + constexpr void
> + __heap_select(_Iter __first, _Iter __middle, _Iter __last, _Comp
> __comp)
> + {
> + ranges::make_heap(__first, __middle, __comp);
> + for (_Iter __i = __middle; __i < __last; ++__i)
> + if (__comp(*__i, *__first))
> + __detail::__pop_heap(__first, __middle, __i, __comp);
> + }
> +
> + template<typename _Iter, typename _Comp>
> + constexpr void
> + __partial_sort(_Iter __first, _Iter __middle, _Iter __last, _Comp
> __comp)
> + {
> + __detail::__heap_select(__first, __middle, __last, __comp);
> + ranges::sort_heap(__first, __middle, __comp);
> + }
> +
> + template<typename _Iter, typename _Comp>
> + constexpr void
> + __introsort_loop(_Iter __first, _Iter __last, unsigned
> __depth_limit, _Comp __comp)
> + {
> + while (__last - __first > __sort_threshold)
> + {
> + if (__depth_limit == 0)
> + {
> + __detail::__partial_sort(__first, __last, __last, __comp);
> + return;
> + }
> + --__depth_limit;
> + _Iter __cut = __detail::__unguarded_partition_pivot(__first,
> __last, __comp);
> + __detail::__introsort_loop(__cut, __last, __depth_limit,
> __comp);
> + __last = __cut;
> + }
> + }
> + } // namespace __detail
> +
> struct __sort_fn
> {
> template<random_access_iterator _Iter, sentinel_for<_Iter> _Sent,
> @@ -2177,10 +2325,21 @@ namespace ranges
> operator()(_Iter __first, _Sent __last,
> _Comp __comp = {}, _Proj __proj = {}) const
> {
> - auto __lasti = ranges::next(__first, __last);
> - _GLIBCXX_STD_A::sort(std::move(__first), __lasti,
> - __detail::__make_comp_proj(__comp, __proj));
> - return __lasti;
> + if constexpr (!same_as<_Iter, _Sent>)
> + return (*this)(__first, ranges::next(__first, __last),
> + std::move(__comp), std::move(__proj));
> + else
> + {
> + if (__first != __last)
> + {
> + auto __comp_proj = __detail::__make_comp_proj(__comp,
> __proj);
> + auto __n = __detail::__to_unsigned_like(__last - __first);
> + unsigned __depth_limit = (std::__bit_width(__n) - 1) * 2;
> + __detail::__introsort_loop(__first, __last, __depth_limit,
> __comp_proj);
> + __detail::__final_insertion_sort(__first, __last,
> __comp_proj);
> + }
> + return __last;
> + }
> }
>
> template<random_access_range _Range,
> diff --git a/libstdc++-v3/testsuite/25_algorithms/sort/118209.cc
> b/libstdc++-v3/testsuite/25_algorithms/sort/118209.cc
> new file mode 100644
> index 000000000000..6dedbde75173
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/25_algorithms/sort/118209.cc
> @@ -0,0 +1,23 @@
> +// PR libstdc++ - ranges::sort doesn't use iter_move, cannot sort zip of
> move-only type
> +// { dg-do compile { target c++23 } }
> +
> +#include <algorithm>
> +#include <ranges>
> +#include <vector>
> +
> +struct F {
> + int a = -1;
> + explicit F(int d) : a(d) { }
> + F(const F&) = delete;
> + F(F&& o) : a(o.a) { }
> + void operator=(const F&) = delete;
> + F& operator=(F&& o) { return *this; }
> + auto operator<=>(const F&) const = default;
> +};
> +
> +int main () {
> + int a[] = {3,2,1};
> + std::vector<F> v(a, a+3);
> + std::ranges::sort(v); // OK
> + std::ranges::sort(std::views::zip(v)); // didn't compile
> +}
> diff --git a/libstdc++-v3/testsuite/25_algorithms/sort/constrained.cc
> b/libstdc++-v3/testsuite/25_algorithms/sort/constrained.cc
> index 82754af96430..930dbd77a376 100644
> --- a/libstdc++-v3/testsuite/25_algorithms/sort/constrained.cc
> +++ b/libstdc++-v3/testsuite/25_algorithms/sort/constrained.cc
> @@ -20,6 +20,7 @@
>
> #include <algorithm>
> #include <random>
> +#include <ranges>
> #include <vector>
> #include <testsuite_hooks.h>
> #include <testsuite_iterators.h>
> @@ -72,9 +73,39 @@ test02()
> && ranges::equal(x, y, {}, &X::i, &X::i));
> }
>
> +constexpr bool
> +test03()
> +{
> + // PR libstdc++/100795 - ranges::sort should not use std::sort directly
> +#if __SIZEOF_INT128__
> + auto v = std::views::iota(__int128(0), __int128(20));
> +#else
> + auto v = std::views::iota(0ll, 20ll);
> +#endif
> +
> + int storage[20] = {2,5,4,3,1,6,7,9,10,8,11,14,12,13,15,16,18,0,19,17};
> + auto w = v | std::views::transform([&](auto i) -> int& { return
> storage[i]; });
> + using type = decltype(w);
> + using cat =
> std::iterator_traits<std::ranges::iterator_t<type>>::iterator_category;
> + static_assert( std::same_as<cat, std::output_iterator_tag> );
> + static_assert( std::ranges::random_access_range<type> );
> +
> + ranges::sort(w);
> + VERIFY( ranges::equal(w, v) );
> +
> + ranges::sort(w, std::ranges::greater{});
> + VERIFY( ranges::equal(w, v | std::views::reverse) );
> +
> + ranges::sort(w, std::ranges::greater{}, std::negate{});
> + VERIFY( ranges::equal(w, v) );
> +
> + return true;
> +}
> +
> int
> main()
> {
> test01();
> static_assert(test02());
> + static_assert(test03());
> }
> --
> 2.50.0.rc2
>
>
