https://gcc.gnu.org/g:1a41e52d7ecb583947a37b8d2e16a0a9ea3777a4
commit r16-3575-g1a41e52d7ecb583947a37b8d2e16a0a9ea3777a4 Author: Tomasz Kamiński <[email protected]> Date: Mon Sep 1 14:37:57 2025 +0200 libstdc++: Reuse _Bind_back_t functor in ranges::_Partial This patch refactors ranges::_Partial to be implemented using _Bind_back_t. This allows it to benefit from the changes in r16-3398-g250dd5b5604fbc, specifically making the closure trivially copyable. Since _Bind_back_t already provides an optimized implementation for a single bound argument, specializations for _Partial with a single argument are now removed. We still preserve a specialization of _Partial for trivially copy-constructible arguments that define only a const overload of operator(). To avoid re-checking invocability constraints, this specialization calls the now-public, unconstrained _Binder::_S_call static method instead of the constrained _Binder::operator(). The primary specialization of _Partial retains its operator(), which uses a simpler __adaptor_invocable constraint that does not consider member pointers, as they are not relevant here. This implementation also calls _Binder::_S_call to avoid re-performing overload resolution and invocability checks for _Binder::operator(). Finally, the _M_binder member (_Bind_back_t) is now marked [[no_unique_address]]. This is beneficial as ranges::_Partial is used with ranges::to, which commonly has zero or empty bound arguments (e.g., stateless allocators, comparators, or hash functions). libstdc++-v3/ChangeLog: * include/bits/binders.h (_Binder::_S_call): Make public. * include/std/ranges (ranges::_Partial<_Adaptor, _Args...>): Replace tuple<_Args...> with _Bind_back_t<_Adaptor, _Args...>. (ranges::_Partial<_Adaptor, _Arg>): Remove. Reviewed-by: Patrick Palka <[email protected]> Reviewed-by: Jonathan Wakely <[email protected]> Signed-off-by: Tomasz Kamiński <[email protected]> Diff: --- libstdc++-v3/include/bits/binders.h | 10 ++-- libstdc++-v3/include/std/ranges | 104 +++++------------------------------- 2 files changed, 17 insertions(+), 97 deletions(-) diff --git a/libstdc++-v3/include/bits/binders.h b/libstdc++-v3/include/bits/binders.h index c324bf51481c..6489edd5321b 100644 --- a/libstdc++-v3/include/bits/binders.h +++ b/libstdc++-v3/include/bits/binders.h @@ -186,11 +186,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION void operator()(_CallArgs&&...) const && = delete; #endif - private: - using _BoundArgsStorage - // _BoundArgs are required to be move-constructible, so this is valid. - = decltype(__make_bound_args<_BoundArgs...>(std::declval<_BoundArgs>()...)); - template<typename _Tp, typename... _CallArgs> static constexpr decltype(auto) @@ -214,6 +209,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION std::forward<_CallArgs>(__call_args)...); } + private: + using _BoundArgsStorage + // _BoundArgs are required to be move-constructible, so this is valid. + = decltype(__make_bound_args<_BoundArgs...>(std::declval<_BoundArgs>()...)); + [[no_unique_address]] _Fd _M_fd; [[no_unique_address]] _BoundArgsStorage _M_bound_args; }; diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index 2970b2cbe00b..156d12b31ba1 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -51,6 +51,7 @@ #include <utility> #include <variant> #endif +#include <bits/binders.h> #include <bits/ranges_util.h> #include <bits/refwrap.h> @@ -1047,14 +1048,15 @@ namespace views::__adaptor template<typename _Adaptor, typename... _Args> struct _Partial : _RangeAdaptorClosure<_Partial<_Adaptor, _Args...>> { - tuple<_Args...> _M_args; + using _Binder = _Bind_back_t<_Adaptor, _Args...>; + [[no_unique_address]] _Binder _M_binder; // First parameter is to ensure this constructor is never used // instead of the copy/move constructor. template<typename... _Ts> constexpr _Partial(int, _Ts&&... __args) - : _M_args(std::forward<_Ts>(__args)...) + : _M_binder(0, _Adaptor(), std::forward<_Ts>(__args)...) { } // Invoke _Adaptor with arguments __r, _M_args... according to the @@ -1065,75 +1067,21 @@ namespace views::__adaptor constexpr auto operator()(this _Self&& __self, _Range&& __r) { - auto __forwarder = [&__r] (auto&&... __args) { - return _Adaptor{}(std::forward<_Range>(__r), - std::forward<decltype(__args)>(__args)...); - }; - return std::apply(__forwarder, __like_t<_Self, _Partial>(__self)._M_args); + return _Binder::_S_call(__like_t<_Self, _Partial>(__self)._M_binder, + std::forward<_Range>(__r)); } #else template<typename _Range> requires __adaptor_invocable<_Adaptor, _Range, const _Args&...> constexpr auto operator()(_Range&& __r) const & - { - auto __forwarder = [&__r] (const auto&... __args) { - return _Adaptor{}(std::forward<_Range>(__r), __args...); - }; - return std::apply(__forwarder, _M_args); - } + { return _Binder::_S_call(_M_binder, std::forward<_Range>(__r)); } template<typename _Range> requires __adaptor_invocable<_Adaptor, _Range, _Args...> constexpr auto operator()(_Range&& __r) && - { - auto __forwarder = [&__r] (auto&... __args) { - return _Adaptor{}(std::forward<_Range>(__r), std::move(__args)...); - }; - return std::apply(__forwarder, _M_args); - } - - template<typename _Range> - constexpr auto - operator()(_Range&& __r) const && = delete; -#endif - }; - - // A lightweight specialization of the above primary template for - // the common case where _Adaptor accepts a single extra argument. - template<typename _Adaptor, typename _Arg> - struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure<_Partial<_Adaptor, _Arg>> - { - _Arg _M_arg; - - template<typename _Tp> - constexpr - _Partial(int, _Tp&& __arg) - : _M_arg(std::forward<_Tp>(__arg)) - { } - -#if __cpp_explicit_this_parameter - template<typename _Self, typename _Range> - requires __adaptor_invocable<_Adaptor, _Range, __like_t<_Self, _Arg>> - constexpr auto - operator()(this _Self&& __self, _Range&& __r) - { - return _Adaptor{}(std::forward<_Range>(__r), - __like_t<_Self, _Partial>(__self)._M_arg); - } -#else - template<typename _Range> - requires __adaptor_invocable<_Adaptor, _Range, const _Arg&> - constexpr auto - operator()(_Range&& __r) const & - { return _Adaptor{}(std::forward<_Range>(__r), _M_arg); } - - template<typename _Range> - requires __adaptor_invocable<_Adaptor, _Range, _Arg> - constexpr auto - operator()(_Range&& __r) && - { return _Adaptor{}(std::forward<_Range>(__r), std::move(_M_arg)); } + { return _Binder::_S_call(std::move(_M_binder), std::forward<_Range>(__r)); } template<typename _Range> constexpr auto @@ -1150,12 +1098,13 @@ namespace views::__adaptor && (is_trivially_copy_constructible_v<_Args> && ...) struct _Partial<_Adaptor, _Args...> : _RangeAdaptorClosure<_Partial<_Adaptor, _Args...>> { - tuple<_Args...> _M_args; + using _Binder = _Bind_back_t<_Adaptor, _Args...>; + [[no_unique_address]] _Binder _M_binder; template<typename... _Ts> constexpr _Partial(int, _Ts&&... __args) - : _M_args(std::forward<_Ts>(__args)...) + : _M_binder(0, _Adaptor(), std::forward<_Ts>(__args)...) { } // Invoke _Adaptor with arguments __r, const _M_args&... regardless @@ -1164,36 +1113,7 @@ namespace views::__adaptor requires __adaptor_invocable<_Adaptor, _Range, const _Args&...> constexpr auto operator()(_Range&& __r) const - { - auto __forwarder = [&__r] (const auto&... __args) { - return _Adaptor{}(std::forward<_Range>(__r), __args...); - }; - return std::apply(__forwarder, _M_args); - } - - static constexpr bool _S_has_simple_call_op = true; - }; - - // A lightweight specialization of the above template for the common case - // where _Adaptor accepts a single extra argument. - template<typename _Adaptor, typename _Arg> - requires __adaptor_has_simple_extra_args<_Adaptor, _Arg> - && is_trivially_copy_constructible_v<_Arg> - struct _Partial<_Adaptor, _Arg> : _RangeAdaptorClosure<_Partial<_Adaptor, _Arg>> - { - _Arg _M_arg; - - template<typename _Tp> - constexpr - _Partial(int, _Tp&& __arg) - : _M_arg(std::forward<_Tp>(__arg)) - { } - - template<typename _Range> - requires __adaptor_invocable<_Adaptor, _Range, const _Arg&> - constexpr auto - operator()(_Range&& __r) const - { return _Adaptor{}(std::forward<_Range>(__r), _M_arg); } + { return _Binder::_S_call(_M_binder, std::forward<_Range>(__r)); } static constexpr bool _S_has_simple_call_op = true; };
