[Bug c++/93259] New: Unsized temporary array initialization problem

[m.cencora at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93259

            Bug ID: 93259
           Summary: Unsized temporary array initialization problem
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: m.cencora at gmail dot com
  Target Milestone: ---

using Array = int[];
auto && array = Array { 1, 2, 3 };

decltype(array) differs depending on if it is declared inside function, or
function template.

I.e. following program fails to compile:
#include <type_traits>

using Array = int[];

template <typename ...Ts>
void bar1(Ts ...)
{
    auto && array = Array{ 1, 2, 3 };

    static_assert(std::is_same<int (&&)[3], decltype(array)>{}, ""); // this
fails, deduces array as int (&&) []
}

template <typename T>
void bar2()
{
    auto && array = Array{ 1, 2, 3 };

    static_assert(std::is_same<int (&&)[3], decltype(array)>{}, "");  // this
fails, deduces array as int (&&) []
}

void bar3()
{
    auto && array = Array{ 1, 2, 3 };

    static_assert(std::is_same<int (&&)[3], decltype(array)>{}, ""); // OK
}

int main()
{
    bar1<int>(1, 2, 3);
    bar2<int>();
    bar3();
}