From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id 3D2E93835432; Fri, 18 Jun 2021 17:46:51 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 3D2E93835432 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 r10-9945] libstdc++: Replace incorrect static assertion in std::reduce [PR95833] X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/releases/gcc-10 X-Git-Oldrev: e5384e746639b2d4084a95605f7be1ef45395768 X-Git-Newrev: 3a37d5c0bd3451104ddab85f69ec37b50d31fa7f Message-Id: <20210618174651.3D2E93835432@sourceware.org> Date: Fri, 18 Jun 2021 17:46:51 +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, 18 Jun 2021 17:46:51 -0000 https://gcc.gnu.org/g:3a37d5c0bd3451104ddab85f69ec37b50d31fa7f commit r10-9945-g3a37d5c0bd3451104ddab85f69ec37b50d31fa7f Author: Jonathan Wakely Date: Fri Jun 18 14:46:58 2021 +0100 libstdc++: Replace incorrect static assertion in std::reduce [PR95833] The standard does not require the iterator's value type to be convertible to the result type, it only requires that the result of dereferencing the iterator can be passed to the binary function. libstdc++-v3/ChangeLog: PR libstdc++/95833 * include/std/numeric (reduce(Iter, Iter, T, BinaryOp)): Replace incorrect static_assert with ones matching the 'Mandates' conditions in the standard. * testsuite/26_numerics/reduce/95833.cc: New test. (cherry picked from commit 0532452dcd17910dfd3d2b0df50dfe3ef1194bf7) Diff: --- libstdc++-v3/include/std/numeric | 6 ++++-- libstdc++-v3/testsuite/26_numerics/reduce/95833.cc | 16 ++++++++++++++++ 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/std/numeric b/libstdc++-v3/include/std/numeric index 6ad73d9713b..03cf719c676 100644 --- a/libstdc++-v3/include/std/numeric +++ b/libstdc++-v3/include/std/numeric @@ -259,9 +259,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION reduce(_InputIterator __first, _InputIterator __last, _Tp __init, _BinaryOperation __binary_op) { - using value_type = typename iterator_traits<_InputIterator>::value_type; + using __ref = typename iterator_traits<_InputIterator>::reference; + static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, _Tp&, __ref>); + static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, __ref, _Tp&>); static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, _Tp&, _Tp&>); - static_assert(is_convertible_v); + static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, __ref, __ref>); if constexpr (__is_random_access_iter<_InputIterator>::value) { while ((__last - __first) >= 4) diff --git a/libstdc++-v3/testsuite/26_numerics/reduce/95833.cc b/libstdc++-v3/testsuite/26_numerics/reduce/95833.cc new file mode 100644 index 00000000000..cf4644f53c9 --- /dev/null +++ b/libstdc++-v3/testsuite/26_numerics/reduce/95833.cc @@ -0,0 +1,16 @@ +// { dg-do compile { target c++17 } } +// PR libstdc++/95833 - Incorrect static_assert in std::reduce overload + +#include + +struct A { }; +struct B { }; + +struct binop +{ + template + A operator()(T&&, U&&) const { return A{}; } +}; + +B b; +A a = std::reduce(&b, &b + 1, A{}, binop{});