[Bug c++/102163] [10/11/12 Regression] std::variant rejects valid constant expression

[ppalka at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102163

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |10.4
   Last reconfirmed|                            |2021-09-01
                 CC|                            |ppalka at gcc dot gnu.org
     Ever confirmed|0                           |1
      Known to work|                            |9.4.0
             Status|UNCONFIRMED                 |ASSIGNED
      Known to fail|                            |10.3.0, 11.2.0, 12.0
            Summary|std::variant rejects valid  |[10/11/12 Regression]
                   |constant expression         |std::variant rejects valid
                   |                            |constant expression

--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Reduced rejects-valid testcase:

struct O {
  constexpr O(int) {}
};

union _Variadic_union
{
  constexpr _Variadic_union() : _M_rest(42) { }
  O _M_rest;
};

constexpr _Variadic_union w;

Started with r10-7313.