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From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r12-4259] libstdc++: Access std::pair members without tuple-like helpers Date: Fri, 8 Oct 2021 23:59:21 +0000 (GMT) [thread overview] Message-ID: <20211008235921.3F60A3858D39@sourceware.org> (raw) https://gcc.gnu.org/g:d87105d697ced10e1f7af3f1f80ef6c9890c8585 commit r12-4259-gd87105d697ced10e1f7af3f1f80ef6c9890c8585 Author: Jonathan Wakely <jwakely@redhat.com> Date: Fri Oct 8 13:41:19 2021 +0100 libstdc++: Access std::pair members without tuple-like helpers This avoids the tuple-like API for std::pair in the unordered containers, removing some overly generic code. The _Select1st projection can figure out the member types of a std::pair without using decltype(std::get<0>(...)). We don't need _Select2nd because it's only needed in _NodeBuilder::_S_build, and that can just access the .second member of the pair directly. The return type of that function doesn't need to be deduced by decltype, we can just expose the __node_type typedef of the node generator. libstdc++-v3/ChangeLog: * include/bits/hashtable_policy.h (_Select1st): Replace use of std::get. (_Select2nd): Remove. (_NodeBuilder::_S_build): Use _NodeGenerator::__node_type typedef instead of deducing it. Remove unnecessary piecewise construction. (_ReuseOrAllocNode): Make __node_type public. (_Map_base): Adjust partial specialization to be able to extract the mapped_type without using tuple_element. (_Map_base::at): Define inline * testsuite/23_containers/unordered_map/requirements/53339.cc: Remove XFAIL. * testsuite/23_containers/unordered_multimap/requirements/53339.cc: Likewise. Diff: --- libstdc++-v3/include/bits/hashtable_policy.h | 130 +++++++++------------ .../unordered_map/requirements/53339.cc | 1 - .../unordered_multimap/requirements/53339.cc | 1 - 3 files changed, 56 insertions(+), 76 deletions(-) diff --git a/libstdc++-v3/include/bits/hashtable_policy.h b/libstdc++-v3/include/bits/hashtable_policy.h index 75488da13f7..994c7b61046 100644 --- a/libstdc++-v3/include/bits/hashtable_policy.h +++ b/libstdc++-v3/include/bits/hashtable_policy.h @@ -87,20 +87,25 @@ namespace __detail struct _Select1st { - template<typename _Tp> - auto - operator()(_Tp&& __x) const noexcept - -> decltype(std::get<0>(std::forward<_Tp>(__x))) - { return std::get<0>(std::forward<_Tp>(__x)); } - }; + template<typename _Pair> + struct __1st_type; + + template<typename _Tp, typename _Up> + struct __1st_type<pair<_Tp, _Up>> + { using type = _Tp; }; + + template<typename _Tp, typename _Up> + struct __1st_type<const pair<_Tp, _Up>> + { using type = const _Tp; }; + + template<typename _Pair> + struct __1st_type<_Pair&> + { using type = typename __1st_type<_Pair>::type&; }; - struct _Select2nd - { template<typename _Tp> - auto + typename __1st_type<_Tp>::type&& operator()(_Tp&& __x) const noexcept - -> decltype(std::get<1>(std::forward<_Tp>(__x))) - { return std::get<1>(std::forward<_Tp>(__x)); } + { return std::forward<_Tp>(__x).first; } }; template<typename _ExKey> @@ -112,14 +117,10 @@ namespace __detail template<typename _Kt, typename _Arg, typename _NodeGenerator> static auto _S_build(_Kt&& __k, _Arg&& __arg, const _NodeGenerator& __node_gen) - -> decltype(__node_gen(std::piecewise_construct, - std::forward_as_tuple(std::forward<_Kt>(__k)), - std::forward_as_tuple(_Select2nd{}( - std::forward<_Arg>(__arg))))) + -> typename _NodeGenerator::__node_type* { - return __node_gen(std::piecewise_construct, - std::forward_as_tuple(std::forward<_Kt>(__k)), - std::forward_as_tuple(_Select2nd{}(std::forward<_Arg>(__arg)))); + return __node_gen(std::forward<_Kt>(__k), + std::forward<_Arg>(__arg).second); } }; @@ -129,7 +130,7 @@ namespace __detail template<typename _Kt, typename _Arg, typename _NodeGenerator> static auto _S_build(_Kt&& __k, _Arg&&, const _NodeGenerator& __node_gen) - -> decltype(__node_gen(std::forward<_Kt>(__k))) + -> typename _NodeGenerator::__node_type* { return __node_gen(std::forward<_Kt>(__k)); } }; @@ -146,9 +147,10 @@ namespace __detail using __hashtable_alloc = _Hashtable_alloc<__node_alloc_type>; using __node_alloc_traits = typename __hashtable_alloc::__node_alloc_traits; - using __node_type = typename __hashtable_alloc::__node_type; public: + using __node_type = typename __hashtable_alloc::__node_type; + _ReuseOrAllocNode(__node_type* __nodes, __hashtable_alloc& __h) : _M_nodes(__nodes), _M_h(__h) { } _ReuseOrAllocNode(const _ReuseOrAllocNode&) = delete; @@ -194,9 +196,10 @@ namespace __detail { private: using __hashtable_alloc = _Hashtable_alloc<_NodeAlloc>; - using __node_type = typename __hashtable_alloc::__node_type; public: + using __node_type = typename __hashtable_alloc::__node_type; + _AllocNode(__hashtable_alloc& __h) : _M_h(__h) { } @@ -667,8 +670,8 @@ namespace __detail /** * Primary class template _Map_base. * - * If the hashtable has a value type of the form pair<T1, T2> and a - * key extraction policy (_ExtractKey) that returns the first part + * If the hashtable has a value type of the form pair<const T1, T2> and + * a key extraction policy (_ExtractKey) that returns the first part * of the pair, the hashtable gets a mapped_type typedef. If it * satisfies those criteria and also has unique keys, then it also * gets an operator[]. @@ -680,37 +683,38 @@ namespace __detail bool _Unique_keys = _Traits::__unique_keys::value> struct _Map_base { }; - /// Partial specialization, __unique_keys set to false. - template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, + /// Partial specialization, __unique_keys set to false, std::pair value type. + template<typename _Key, typename _Val, typename _Alloc, typename _Equal, typename _Hash, typename _RangeHash, typename _Unused, typename _RehashPolicy, typename _Traits> - struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, + struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, false> { - using mapped_type = typename std::tuple_element<1, _Pair>::type; + using mapped_type = _Val; }; /// Partial specialization, __unique_keys set to true. - template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, + template<typename _Key, typename _Val, typename _Alloc, typename _Equal, typename _Hash, typename _RangeHash, typename _Unused, typename _RehashPolicy, typename _Traits> - struct _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, + struct _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true> { private: - using __hashtable_base = _Hashtable_base<_Key, _Pair, _Select1st, _Equal, - _Hash, _RangeHash, _Unused, + using __hashtable_base = _Hashtable_base<_Key, pair<const _Key, _Val>, + _Select1st, _Equal, _Hash, + _RangeHash, _Unused, _Traits>; - using __hashtable = _Hashtable<_Key, _Pair, _Alloc, _Select1st, _Equal, - _Hash, _RangeHash, + using __hashtable = _Hashtable<_Key, pair<const _Key, _Val>, _Alloc, + _Select1st, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>; using __hash_code = typename __hashtable_base::__hash_code; public: using key_type = typename __hashtable_base::key_type; - using mapped_type = typename std::tuple_element<1, _Pair>::type; + using mapped_type = _Val; mapped_type& operator[](const key_type& __k); @@ -721,17 +725,29 @@ namespace __detail // _GLIBCXX_RESOLVE_LIB_DEFECTS // DR 761. unordered_map needs an at() member function. mapped_type& - at(const key_type& __k); + at(const key_type& __k) + { + auto __ite = static_cast<__hashtable*>(this)->find(__k); + if (!__ite._M_cur) + __throw_out_of_range(__N("unordered_map::at")); + return __ite->second; + } const mapped_type& - at(const key_type& __k) const; + at(const key_type& __k) const + { + auto __ite = static_cast<const __hashtable*>(this)->find(__k); + if (!__ite._M_cur) + __throw_out_of_range(__N("unordered_map::at")); + return __ite->second; + } }; - template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, + template<typename _Key, typename _Val, typename _Alloc, typename _Equal, typename _Hash, typename _RangeHash, typename _Unused, typename _RehashPolicy, typename _Traits> auto - _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, + _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>:: operator[](const key_type& __k) -> mapped_type& @@ -754,11 +770,11 @@ namespace __detail return __pos->second; } - template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, + template<typename _Key, typename _Val, typename _Alloc, typename _Equal, typename _Hash, typename _RangeHash, typename _Unused, typename _RehashPolicy, typename _Traits> auto - _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, + _Map_base<_Key, pair<const _Key, _Val>, _Alloc, _Select1st, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>:: operator[](key_type&& __k) -> mapped_type& @@ -781,40 +797,6 @@ namespace __detail return __pos->second; } - template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, - typename _Hash, typename _RangeHash, typename _Unused, - typename _RehashPolicy, typename _Traits> - auto - _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, - _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>:: - at(const key_type& __k) - -> mapped_type& - { - __hashtable* __h = static_cast<__hashtable*>(this); - auto __ite = __h->find(__k); - - if (!__ite._M_cur) - __throw_out_of_range(__N("_Map_base::at")); - return __ite->second; - } - - template<typename _Key, typename _Pair, typename _Alloc, typename _Equal, - typename _Hash, typename _RangeHash, typename _Unused, - typename _RehashPolicy, typename _Traits> - auto - _Map_base<_Key, _Pair, _Alloc, _Select1st, _Equal, - _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits, true>:: - at(const key_type& __k) const - -> const mapped_type& - { - const __hashtable* __h = static_cast<const __hashtable*>(this); - auto __ite = __h->find(__k); - - if (!__ite._M_cur) - __throw_out_of_range(__N("_Map_base::at")); - return __ite->second; - } - /** * Primary class template _Insert_base. * diff --git a/libstdc++-v3/testsuite/23_containers/unordered_map/requirements/53339.cc b/libstdc++-v3/testsuite/23_containers/unordered_map/requirements/53339.cc index 077aa8ba414..c4fe5ad8ed7 100644 --- a/libstdc++-v3/testsuite/23_containers/unordered_map/requirements/53339.cc +++ b/libstdc++-v3/testsuite/23_containers/unordered_map/requirements/53339.cc @@ -1,5 +1,4 @@ // { dg-do compile { target c++11 } } -// { dg-excess-errors "XFAIL because of PR libstdc++/55043 fix" } // Copyright (C) 2012-2021 Free Software Foundation, Inc. // diff --git a/libstdc++-v3/testsuite/23_containers/unordered_multimap/requirements/53339.cc b/libstdc++-v3/testsuite/23_containers/unordered_multimap/requirements/53339.cc index ab33123dad7..de012647953 100644 --- a/libstdc++-v3/testsuite/23_containers/unordered_multimap/requirements/53339.cc +++ b/libstdc++-v3/testsuite/23_containers/unordered_multimap/requirements/53339.cc @@ -1,5 +1,4 @@ // { dg-do compile { target c++11 } } -// { dg-excess-errors "XFAIL because of PR libstdc++/55043 fix" } // Copyright (C) 2012-2021 Free Software Foundation, Inc. //
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