[clang][bytecode] addressof is not constexpr

[k-arrows]

Reproducer:
https://godbolt.org/z/7j8YTGGM9

template <typename T> constexpr inline T *addressof(T &x) noexcept {
  return __builtin_addressof(x);
}

struct T {
  static T tt;
  constexpr T() : p(addressof(tt)) {}
  constexpr T *operator&() const { return p; }
  T *p;
};
constexpr T t;
T T::tt;
static_assert(&t == __builtin_addressof(T::tt), "");
static_assert(&t == addressof(T::tt), "");

When the above program is compiled with option -fexperimental-new-constant-interpreter enabled, it fails. When the option is disabled, it succeeds as expected.

[tbaederr]

This isn't about addressof, it's about member pointers. The diagnostics state that the comparison failed, not that addressof isn't constexpr.

[frederick-vs-ja]

A furtherly reduced example which shows that __builtin_addressof/addressof is unrelated. Godbolt link.

struct T {
  static T tt;
  constexpr T() : p(&tt) {}
  T *p;
};
T T::tt;
constexpr T t;

static_assert(t.p == &T::tt);

This bug is not triggered if &tt is put into a default member initializer and the default constructor is defaulted.