public inbox for gcc-cvs@sourceware.org help / color / mirror / Atom feed
From: Jonathan Wakely <redi@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r13-4745] libstdc++: Fix self-move for std::weak_ptr [PR108118] Date: Fri, 16 Dec 2022 14:30:45 +0000 (GMT) [thread overview] Message-ID: <20221216143045.25E3F3836791@sourceware.org> (raw) https://gcc.gnu.org/g:92eb0adc14a5f84acce7e5bc780b81b1544b24aa commit r13-4745-g92eb0adc14a5f84acce7e5bc780b81b1544b24aa Author: Jonathan Wakely <jwakely@redhat.com> 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. 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 d9230b72203..c22b397a194 100644 --- a/libstdc++-v3/include/bits/shared_ptr_base.h +++ b/libstdc++-v3/include/bits/shared_ptr_base.h @@ -2049,9 +2049,7 @@ _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 <memory> +#include <testsuite_hooks.h> + +void +test_self_move() +{ + std::shared_ptr<int> sp(new int(66)); + std::weak_ptr<int> wp(sp); + wp = std::move(wp); // PR libstdc++/108118 + std::shared_ptr<int> sp2(wp); + VERIFY(sp2 == sp); +} + +int main() +{ + test_self_move(); +}
reply other threads:[~2022-12-16 14:30 UTC|newest] Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20221216143045.25E3F3836791@sourceware.org \ --to=redi@gcc.gnu.org \ --cc=gcc-cvs@gcc.gnu.org \ --cc=libstdc++-cvs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).