From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id 5C62F39ADC3F; Fri, 11 Jun 2021 22:25:47 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5C62F39ADC3F 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 r11-8557] libstdc++: Implement LWG 3403 for std::ranges::ssize X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/releases/gcc-11 X-Git-Oldrev: 950535915868cd0b7f3dbad4321de913f01bddfc X-Git-Newrev: 1112f1226a27cd772aec7e50514a121c5c04bdb7 Message-Id: <20210611222547.5C62F39ADC3F@sourceware.org> Date: Fri, 11 Jun 2021 22:25:47 +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: Fri, 11 Jun 2021 22:25:47 -0000 https://gcc.gnu.org/g:1112f1226a27cd772aec7e50514a121c5c04bdb7 commit r11-8557-g1112f1226a27cd772aec7e50514a121c5c04bdb7 Author: Jonathan Wakely Date: Fri Jun 4 20:28:04 2021 +0100 libstdc++: Implement LWG 3403 for std::ranges::ssize I already changed the constraints for ranges::ssize to use ranges::size, this implements the rest of LWG 3403, so that the returned type is the signed type corresponding to the result of ranges::size. Signed-off-by: Jonathan Wakely libstdc++-v3/ChangeLog: * include/bits/ranges_base.h (_SSize): Return the result of ranges::size converted to the wider of make-signed-like-t and ptrdiff_t, rather than the ranges different type. * testsuite/std/ranges/access/ssize.cc: Adjust expected result for an iota_view that uses an integer class type for its difference_type. (cherry picked from commit 621ea10ca060ba19ec693aa73b5e29d553cca849) Diff: --- libstdc++-v3/include/bits/ranges_base.h | 22 ++++++++++++++++------ libstdc++-v3/testsuite/std/ranges/access/ssize.cc | 9 ++++++--- 2 files changed, 22 insertions(+), 9 deletions(-) diff --git a/libstdc++-v3/include/bits/ranges_base.h b/libstdc++-v3/include/bits/ranges_base.h index 61d91eb8389..e3c3962bcd9 100644 --- a/libstdc++-v3/include/bits/ranges_base.h +++ b/libstdc++-v3/include/bits/ranges_base.h @@ -425,22 +425,32 @@ namespace ranges struct _SSize { + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3403. Domain of ranges::ssize(E) doesn't match ranges::size(E) template requires requires (_Tp& __t) { _Size{}(__t); } constexpr auto operator()(_Tp&& __t) const noexcept(noexcept(_Size{}(__t))) { - using __iter_type = decltype(_Begin{}(__t)); - using __diff_type = iter_difference_t<__iter_type>; - using __gnu_cxx::__int_traits; auto __size = _Size{}(__t); - if constexpr (integral<__diff_type>) + using __size_type = decltype(__size); + // Return the wider of ptrdiff_t and make-signed-like-t<__size_type>. + if constexpr (integral<__size_type>) { - if constexpr (__int_traits<__diff_type>::__digits + using __gnu_cxx::__int_traits; + if constexpr (__int_traits<__size_type>::__digits < __int_traits::__digits) return static_cast(__size); + else + return static_cast>(__size); } - return static_cast<__diff_type>(__size); +#if defined __STRICT_ANSI__ && defined __SIZEOF_INT128__ + // For strict-ansi modes integral<__int128> is false + else if constexpr (__detail::__is_int128<__size_type>) + return static_cast(__size); +#endif + else // Must be one of __max_diff_type or __max_size_type. + return __detail::__max_diff_type(__size); } }; diff --git a/libstdc++-v3/testsuite/std/ranges/access/ssize.cc b/libstdc++-v3/testsuite/std/ranges/access/ssize.cc index b00ec5db1f8..f53f462580c 100644 --- a/libstdc++-v3/testsuite/std/ranges/access/ssize.cc +++ b/libstdc++-v3/testsuite/std/ranges/access/ssize.cc @@ -76,9 +76,12 @@ void test06() { auto i = std::views::iota(1ull, 5u); - auto s = std::ranges::ssize(i); - using R = std::ranges::range_difference_t; - static_assert( std::same_as ); + auto s = std::ranges::size(i); + auto ss = std::ranges::ssize(i); + // std::ranges::range_difference_t is larger than long long, + // but LWG 3403 says ranges::ssize(i) returns the signed version of the + // type that ranges::size(i) returns, not the range's difference_type. + static_assert( std::same_as> ); VERIFY( s == 4 ); }