From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id 5460A3858C52; Thu, 2 Feb 2023 16:47:43 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5460A3858C52 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1675356463; bh=n88JFKWIAdWJ1rz4CUjZG7EOm3pLU7gqpMfZbG23DRA=; h=From:To:Subject:Date:From; b=t4MnwpIC+pdbzl9eluVJY90EmWrXN68rUSG76ITqFA1dz8I6UvkakGV4MUdLF4mqr J4vghdQKFVXC3Kj8xOZdPJs+WqJflS7+jgrGjWViAWAV4bk2uhoXQD6BHNUcFAqdXp lOYh3Rnn8RUo/S9kpkT9rT24fxglzvqpcVb01kuw= 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 r13-5661] libstdc++: Use emplace in std::variant::operator=(T&&) as per LWG 3585 X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/master X-Git-Oldrev: f25dd779d44fb75a6c5e1c73e5bf2c85af180026 X-Git-Newrev: 1395415fdc2d60e5346dbcf476749daf42d5b724 Message-Id: <20230202164743.5460A3858C52@sourceware.org> Date: Thu, 2 Feb 2023 16:47:43 +0000 (GMT) List-Id: https://gcc.gnu.org/g:1395415fdc2d60e5346dbcf476749daf42d5b724 commit r13-5661-g1395415fdc2d60e5346dbcf476749daf42d5b724 Author: Jonathan Wakely Date: Wed Feb 1 20:54:22 2023 +0000 libstdc++: Use emplace in std::variant::operator=(T&&) as per LWG 3585 This was approved at the October 2021 plenary. libstdc++-v3/ChangeLog: * include/std/variant (variant::operator=): Implement resolution of LWG 3585. * testsuite/20_util/variant/lwg3585.cc: New test. Diff: --- libstdc++-v3/include/std/variant | 4 +++- libstdc++-v3/testsuite/20_util/variant/lwg3585.cc | 16 ++++++++++++++++ 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant index 35781495e31..5155124522f 100644 --- a/libstdc++-v3/include/std/variant +++ b/libstdc++-v3/include/std/variant @@ -1481,7 +1481,9 @@ namespace __variant || !is_nothrow_move_constructible_v<_Tj>) this->emplace<__index>(std::forward<_Tp>(__rhs)); else - operator=(variant(std::forward<_Tp>(__rhs))); + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 3585. converting assignment with immovable alternative + this->emplace<__index>(_Tj(std::forward<_Tp>(__rhs))); } return *this; } diff --git a/libstdc++-v3/testsuite/20_util/variant/lwg3585.cc b/libstdc++-v3/testsuite/20_util/variant/lwg3585.cc new file mode 100644 index 00000000000..0cbfc0db7f5 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/variant/lwg3585.cc @@ -0,0 +1,16 @@ +// { dg-do compile { target c++17 } } + +// LWG 3585. Variant converting assignment with immovable alternative + +#include +#include + +struct A { + A() = default; + A(A&&) = delete; +}; + +int main() { + std::variant v; + v = "hello"; +}