From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id 6C8EA3858C53; Tue, 12 Jul 2022 08:39:09 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6C8EA3858C53 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jonathan Wakely To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r13-1612] libstdc++: Prefer const T to std::add_const_t X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/master X-Git-Oldrev: 3723aedaad20a129741c2f6f3c22b3dd1220a3fc X-Git-Newrev: 8be17e2ac73d43fd9781b842d47b0c3df2578756 Message-Id: <20220712083909.6C8EA3858C53@sourceware.org> Date: Tue, 12 Jul 2022 08:39:09 +0000 (GMT) X-BeenThere: libstdc++-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Jul 2022 08:39:09 -0000 https://gcc.gnu.org/g:8be17e2ac73d43fd9781b842d47b0c3df2578756 commit r13-1612-g8be17e2ac73d43fd9781b842d47b0c3df2578756 Author: Jonathan Wakely Date: Thu Jul 7 12:27:08 2022 +0100 libstdc++: Prefer const T to std::add_const_t For any typedef-name or template parameter, T, add_const_t is equivalent to T const, so we can avoid instantiating the std::add_const class template and just say T const (or const T). This isn't true for a non-typedef like int&, where int& const would be ill-formed, but we shouldn't be using add_const_t anyway, because we know what that type is. The only place we need to continue using std::add_const is in the std::bind implementation where it's used as a template template parameter to be applied as a metafunction elsewhere. libstdc++-v3/ChangeLog: * include/bits/stl_iterator.h (__iter_to_alloc_t): Replace add_const_t with const-qualifier. * include/bits/utility.h (tuple_element): Likewise for all cv-qualifiers. * include/std/type_traits (add_const, add_volatile): Replace typedef-declaration with using-declaration. (add_cv): Replace add_const and add_volatile with cv-qualifiers. * include/std/variant (variant_alternative): Replace add_const_t, add_volatile_t and add_cv_t etc. with cv-qualifiers. Diff: --- libstdc++-v3/include/bits/stl_iterator.h | 11 +++++------ libstdc++-v3/include/bits/utility.h | 6 +++--- libstdc++-v3/include/std/type_traits | 9 +++------ libstdc++-v3/include/std/variant | 6 +++--- 4 files changed, 14 insertions(+), 18 deletions(-) diff --git a/libstdc++-v3/include/bits/stl_iterator.h b/libstdc++-v3/include/bits/stl_iterator.h index 12a89ab229f..049cb02a4c4 100644 --- a/libstdc++-v3/include/bits/stl_iterator.h +++ b/libstdc++-v3/include/bits/stl_iterator.h @@ -2536,19 +2536,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // of associative containers. template using __iter_key_t = remove_const_t< - typename iterator_traits<_InputIterator>::value_type::first_type>; + typename iterator_traits<_InputIterator>::value_type::first_type>; template - using __iter_val_t = - typename iterator_traits<_InputIterator>::value_type::second_type; + using __iter_val_t + = typename iterator_traits<_InputIterator>::value_type::second_type; template struct pair; template - using __iter_to_alloc_t = - pair>, - __iter_val_t<_InputIterator>>; + using __iter_to_alloc_t + = pair, __iter_val_t<_InputIterator>>; #endif // __cpp_deduction_guides _GLIBCXX_END_NAMESPACE_VERSION diff --git a/libstdc++-v3/include/bits/utility.h b/libstdc++-v3/include/bits/utility.h index e0e40309a6d..6a192e27836 100644 --- a/libstdc++-v3/include/bits/utility.h +++ b/libstdc++-v3/include/bits/utility.h @@ -86,19 +86,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template struct tuple_element<__i, const _Tp> { - typedef typename add_const<__tuple_element_t<__i, _Tp>>::type type; + using type = const __tuple_element_t<__i, _Tp>; }; template struct tuple_element<__i, volatile _Tp> { - typedef typename add_volatile<__tuple_element_t<__i, _Tp>>::type type; + using type = volatile __tuple_element_t<__i, _Tp>; }; template struct tuple_element<__i, const volatile _Tp> { - typedef typename add_cv<__tuple_element_t<__i, _Tp>>::type type; + using type = const volatile __tuple_element_t<__i, _Tp>; }; #if __cplusplus >= 201402L diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits index 2572d8edd69..e5f58bc2e3f 100644 --- a/libstdc++-v3/include/std/type_traits +++ b/libstdc++-v3/include/std/type_traits @@ -1577,20 +1577,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION /// add_const template struct add_const - { typedef _Tp const type; }; + { using type = _Tp const; }; /// add_volatile template struct add_volatile - { typedef _Tp volatile type; }; + { using type = _Tp volatile; }; /// add_cv template struct add_cv - { - typedef typename - add_const::type>::type type; - }; + { using type = _Tp const volatile; }; #if __cplusplus > 201103L diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant index 5ff1e3edcdf..f8f15665433 100644 --- a/libstdc++-v3/include/std/variant +++ b/libstdc++-v3/include/std/variant @@ -107,15 +107,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template struct variant_alternative<_Np, const _Variant> - { using type = add_const_t>; }; + { using type = const variant_alternative_t<_Np, _Variant>; }; template struct variant_alternative<_Np, volatile _Variant> - { using type = add_volatile_t>; }; + { using type = volatile variant_alternative_t<_Np, _Variant>; }; template struct variant_alternative<_Np, const volatile _Variant> - { using type = add_cv_t>; }; + { using type = const volatile variant_alternative_t<_Np, _Variant>; }; inline constexpr size_t variant_npos = -1;