https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104163
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2022-01-21
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The deeply nested case was:
at.C:9:48: error: 'std::atomic<std::shared_ptr<int>
>{std::_Sp_atomic<std::shared_ptr<int> >{std::_Sp_atomic<std::shared_ptr<int>
>::_Atomic_count{std::__atomic_base<long unsigned int>{0}}}}' is not a constant
expression
The real problem was a member of _Sp_atomic, so everything about
std::_Sp_atomic<std::shared_ptr<int> >::_Atomic_count{std::__atomic_base<long
unsigned int>{0}} was a red herring.
Simplified:
struct atomic_base
{
constexpr atomic_base(int i) : i(i) { }
int i{0};
};
struct Sp_atomic
{
struct Atomic_count
{
constexpr Atomic_count() = default;
atomic_base a{0};
};
void* ptr;
Atomic_count c{};
constexpr Sp_atomic() = default;
};
struct atomic
{
constexpr atomic() = default;
Sp_atomic s;
};
constinit atomic a{};
mut.C:27:18: error: 'constinit' variable 'a' does not have a constant
initializer
27 | constinit atomic a{};
| ^
mut.C:27:20: error:
'atomic{Sp_atomic{Sp_atomic::Atomic_count{atomic_base{0}}}}' is not a constant
expression
27 | constinit atomic a{};
| ^
mut.C:27:20: error: 'atomic()' is not a constant expression because it refers
to an incompletely initialized variable
