[Bug c++/118047] [12/13/14/15 Regression] Incorrect list initialization of vector of struct of array of struct of enum since r12-7803-gf0530882d99abc

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118047

--- Comment #11 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
More reduced.  Note that if initializer_list isn't in std, the assert fails
even with clang++ and g++11.

```
// PR c++/118047

typedef decltype(sizeof(char)) size_t;

namespace std {
template <typename T>
struct initializer_list {
  const T *_M_array;
  size_t _M_len;
  constexpr size_t size() const { return _M_len; }
};
}

enum E {
    One
};

struct A {
    E e = One;
};

struct B {
    A as[1] {};
};

struct v
{
  constexpr v(const std::initializer_list<B> &a) : size(a.size()){}
  int size;
};

constexpr v a{{}};

static_assert(a.size == 1);
```