[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 Patrick Palka changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED Target Milestone|--- |11.3 --- Comment #10 from Patrick Palka --- Fixed for GCC 11.3 and 12. (10.4 doesn't implement this partial specialization of __box)
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 Patrick Palka changed: What|Removed |Added Target Milestone|11.3|11.2 --- Comment #11 from Patrick Palka --- Er, this was actually already fixed for 11.2
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 Patrick Palka changed: What|Removed |Added Last reconfirmed||2021-05-07 Assignee|unassigned at gcc dot gnu.org |ppalka at gcc dot gnu.org Status|UNCONFIRMED |ASSIGNED Ever confirmed|0 |1 CC||ppalka at gcc dot gnu.org --- Comment #1 from Patrick Palka --- Confirmed.
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475
--- Comment #2 from 康桓瑋 ---
Reduced example:
#include
struct S {
S() = default;
S(int, int) {}
S(std::initializer_list) = delete;
};
std::ranges::single_view single(std::in_place, 0, 0);
https://godbolt.org/z/d1bE8sPdd
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 --- Comment #3 from 康桓瑋 --- Also, the operator->() simply uses operator& instead of std::__addressof. https://godbolt.org/z/zfGnEoePG
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 --- Comment #4 from 康桓瑋 --- (In reply to 康桓瑋 from comment #3) > Also, the operator->() simply uses operator& instead of std::__addressof. > > https://godbolt.org/z/zfGnEoePG Another issue is that the has_value() of this specialization will always return true, which will make the precondition __glibcxx_assert(_M_pred.has_value()) for filter_view's begin() almost useless. Although it is not clear why semiregular-box is partial specialization in gcc-11, it is obvious that this needs to be treated with care.
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 --- Comment #5 from Patrick Palka --- (In reply to 康桓瑋 from comment #4) > (In reply to 康桓瑋 from comment #3) > > Also, the operator->() simply uses operator& instead of std::__addressof. > > > > https://godbolt.org/z/zfGnEoePG Good catch, thanks. > > Another issue is that the has_value() of this specialization will always > return true, which will make the precondition > __glibcxx_assert(_M_pred.has_value()) for filter_view's begin() almost > useless. That's fine I suppose, the assert will just be a no-op in that case. > > Although it is not clear why semiregular-box is partial specialization in > gcc-11, it is obvious that this needs to be treated with care. The advantage of the partial specialization is that it's space-optimal whereas the primary template is not, due to its use of std::optional.
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 --- Comment #6 from CVS Commits --- The master branch has been updated by Patrick Palka : https://gcc.gnu.org/g:fe993b469c528230d9a01e1ae2208610f960dd9f commit r12-856-gfe993b469c528230d9a01e1ae2208610f960dd9f Author: Patrick Palka 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.
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475
--- Comment #7 from 康桓瑋 ---
(In reply to CVS Commits from comment #6)
> The master branch has been updated by Patrick Palka :
>
> https://gcc.gnu.org/g:fe993b469c528230d9a01e1ae2208610f960dd9f
>
> commit r12-856-gfe993b469c528230d9a01e1ae2208610f960dd9f
> Author: Patrick Palka
> 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
struct S {
S() = default;
S(std::initializer_list) = delete;
S(const S&) {}
};
S obj;
auto l = std::initializer_list{{}, {}};
auto x = std::views::single(obj);
auto y = std::views::single(std::move(l));
https://godbolt.org/z/7nePj6Y57
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 --- Comment #8 from Jonathan Wakely --- We should almost never use list-init in the library unless the standard explicitly specifies it. Even if the standard specifies it, we should consider whether that's a defect in the standard. Uniform init is uniformly bad.
[Bug libstdc++/100475] semiregular-box's constructor uses wrong list-initialization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100475 --- Comment #9 from CVS Commits --- The releases/gcc-11 branch has been updated by Patrick Palka : https://gcc.gnu.org/g:258aedd9ad1ea4597528632e93dee860acc2eaf5 commit r11-8566-g258aedd9ad1ea4597528632e93dee860acc2eaf5 Author: Patrick Palka 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. (cherry picked from commit fe993b469c528230d9a01e1ae2208610f960dd9f)
