From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id 89088385B522; Fri, 23 Jun 2023 16:13:08 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 89088385B522 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1687536788; bh=MOqstDDnmmF8kz4Bl48eKRawUV0fR3UEgAoac7Qjmjw=; h=From:To:Subject:Date:From; b=sS014JO2id7rc2Qkl+SsKgMEkP6baIfYMQTf4nkeOx6AhSOy4M4VP4BWZgzu6DhNU isornc4vKTwyHRJ+TSSk7HsNP4DSPkClpmZqpkZek/0CX6oOlSzkqs4q7tAmFdy9lq 6HkcsyuGxqnbUarcS5keC8c5q5RFmBwb4OmBaMo0= 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 r10-11469] libstdc++: Fix self-move for std::weak_ptr [PR108118] X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/releases/gcc-10 X-Git-Oldrev: 7dba69b5e9977408921c635681a0daa34b813e16 X-Git-Newrev: b272bc0fbf84454cae8c02e7404cfb23641380cd Message-Id: <20230623161308.89088385B522@sourceware.org> Date: Fri, 23 Jun 2023 16:13:08 +0000 (GMT) List-Id: https://gcc.gnu.org/g:b272bc0fbf84454cae8c02e7404cfb23641380cd commit r10-11469-gb272bc0fbf84454cae8c02e7404cfb23641380cd Author: Jonathan Wakely Date: Thu Dec 15 09:52:48 2022 +0000 libstdc++: Fix self-move for std::weak_ptr [PR108118] I think an alternative fix would be something like: _M_ptr = std::exchange(rhs._M_ptr, nullptr); _M_refcount = std::move(rhs._M_refcount); The standard's move-and-swap implementation generates smaller code at all levels except -O0 and -Og, so it seems simplest to just do what the standard says. libstdc++-v3/ChangeLog: PR libstdc++/108118 * include/bits/shared_ptr_base.h (weak_ptr::operator=): Implement as move-and-swap exactly as specified in the standard. * testsuite/20_util/weak_ptr/cons/self_move.cc: New test. (cherry picked from commit 92eb0adc14a5f84acce7e5bc780b81b1544b24aa) Diff: --- libstdc++-v3/include/bits/shared_ptr_base.h | 4 +--- .../testsuite/20_util/weak_ptr/cons/self_move.cc | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+), 3 deletions(-) diff --git a/libstdc++-v3/include/bits/shared_ptr_base.h b/libstdc++-v3/include/bits/shared_ptr_base.h index 792d8344664..c66d895997d 100644 --- a/libstdc++-v3/include/bits/shared_ptr_base.h +++ b/libstdc++-v3/include/bits/shared_ptr_base.h @@ -1700,9 +1700,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION __weak_ptr& operator=(__weak_ptr&& __r) noexcept { - _M_ptr = __r._M_ptr; - _M_refcount = std::move(__r._M_refcount); - __r._M_ptr = nullptr; + __weak_ptr(std::move(__r)).swap(*this); return *this; } diff --git a/libstdc++-v3/testsuite/20_util/weak_ptr/cons/self_move.cc b/libstdc++-v3/testsuite/20_util/weak_ptr/cons/self_move.cc new file mode 100644 index 00000000000..c890d2ba94d --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/weak_ptr/cons/self_move.cc @@ -0,0 +1,19 @@ +// { dg-do run { target c++11 } } + +#include +#include + +void +test_self_move() +{ + std::shared_ptr sp(new int(66)); + std::weak_ptr wp(sp); + wp = std::move(wp); // PR libstdc++/108118 + std::shared_ptr sp2(wp); + VERIFY(sp2 == sp); +} + +int main() +{ + test_self_move(); +}