https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475
--- Comment #7 from 康桓瑋 <hewillk at gmail dot com> --- (In reply to CVS Commits from comment #6) > The master branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: > > https://gcc.gnu.org/g:fe993b469c528230d9a01e1ae2208610f960dd9f > > commit r12-856-gfe993b469c528230d9a01e1ae2208610f960dd9f > Author: Patrick Palka <ppa...@redhat.com> > Date: Tue May 18 00:28:44 2021 -0400 > > libstdc++: Fix up semiregular-box partial specialization [PR100475] > > This makes the in-place constructor of our partial specialization of > __box for already-semiregular types perform > direct-non-list-initialization > (in accordance with the specification of the primary template), and > additionally makes the member function data() use std::__addressof. > > libstdc++-v3/ChangeLog: > > PR libstdc++/100475 > * include/std/ranges (__box::__box): Use non-list-initialization > in member initializer list of in-place constructor of the > partial specialization for semiregular types. > (__box::operator->): Use std::__addressof. > * testsuite/std/ranges/adaptors/detail/semiregular_box.cc > (test02): New test. > * testsuite/std/ranges/single_view.cc (test04): New test. I think that even list-initialization with a single parameter should be changed to direct-non-list-initialization to avoid bugs in some uncommon situations. #include <ranges> struct S { S() = default; S(std::initializer_list<S>) = delete; S(const S&) {} }; S obj; auto l = std::initializer_list<S>{{}, {}}; auto x = std::views::single(obj); auto y = std::views::single(std::move(l)); https://godbolt.org/z/7nePj6Y57
