[Bug c++/92869] New: g++ wrongly reports aggregate type as not-aggregate (when explicitly defaulted ctors are added)

[igor.chorazewicz at intel dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92869

            Bug ID: 92869
           Summary: g++ wrongly reports aggregate type as not-aggregate
                    (when explicitly defaulted ctors are added)
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: igor.chorazewicz at intel dot com
  Target Milestone: ---

The following code, when compiled with -std=c++17 results in "0" being printed.
The correct behavior is to print "1". Removing ctors fixes the issue, however,
accordingly to the standard, explicitly defaulted ctors are allowed for an
aggregate.

#include <array>
#include <type_traits>
#include <iostream>

template <typename T, std::size_t N>
struct A {
    A() = default;
    A(const A &) = default;
    A(A &&) = default;

    T arr[N];   
};

int main()
{
    std::cout << std::is_aggregate<A<int,3>>::value;
}