https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103891
Bug ID: 103891
Summary: clang-13 fails to compile libstdc++'s
std::variant<std::vector<int>>: error: attempt to use
a deleted function
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: slyfox at gcc dot gnu.org
Target Milestone: ---
Initially I observed the error as a mold-1.0.0 build failure on clang-13 which
uses gcc-12's libstdc++. Here is a one line reproducer:
#include <variant>
#include <vector>
std::variant<std::vector<long> > v;
$ /tmp/gcc-12/bin/c++ -std=c++20 -c tapi.cc
$ /tmp/clang-13/bin/c++ -std=c++20 -c tapi.cc
/<<NIX>>/gcc-12.0.0/include/c++/12.0.0/variant:460:2: error: attempt to use a
deleted function
_Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
^
/<<NIX>>/gcc-12.0.0/include/c++/12.0.0/variant:747:4: note: in instantiation of
function template specialization
'std::__detail::__variant::_Variant_storage<false,
std::vector<long>>::_Variant_storage<0UL>' requested here
: _Base(__i, std::forward<_Args>(__args)...)
^
/<<NIX>>/gcc-12.0.0/include/c++/12.0.0/variant:742:9: note: in instantiation of
function template specialization
'std::__detail::__variant::_Variant_base<std::vector<long>>::_Variant_base<0UL>'
requested here
: _Variant_base(in_place_index<0>) { }
^
/<<NIX>>/gcc-12.0.0/include/c++/12.0.0/variant:1403:7: note: in instantiation
of member function
'std::__detail::__variant::_Variant_base<std::vector<long>>::_Variant_base'
requested here
variant() = default;
^
...
I attempted to reduce it down to something manageable but ended up with
something else: https://github.com/llvm/llvm-project/issues/52956
I don't really understand how requires() works.
Should libstdc++ work as is against clang++? Does it perhaps need a small
tweak?
Thank you!
