-
-namespace portability_detail {
-
-template <typename I, I A, I B>
-using integral_max = std::integral_constant<I, (A < B) ? B : A>;
-
-template <typename I, I A, I... Bs>
-struct integral_sequence_max
- : integral_max<I, A, integral_sequence_max<I, Bs...>::value> {};
-
-template <typename I, I A>
-struct integral_sequence_max<I, A> : std::integral_constant<I, A> {};
-
-template <typename... Ts>
-using max_alignment = integral_sequence_max<size_t, alignof(Ts)...>;
-
-using max_basic_alignment = max_alignment<
- std::max_align_t,
- long double,
- double,
- float,
- long long int,
- long int,
- int,
- short int,
- bool,
- char,
- char16_t,
- char32_t,
- wchar_t,
- std::nullptr_t>;
-} // namespace portability_detail
-
-constexpr size_t max_align_v = portability_detail::max_basic_alignment::value;
-
-// max_align_t is a type which is aligned at least as strictly as the
-// most-aligned basic type (see the specification of std::max_align_t). This
-// implementation exists because 32-bit iOS platforms have a broken
-// std::max_align_t (see below).
-//
-// You should refer to this as `::folly::max_align_t` in portable code, even if
-// you have `using namespace folly;` because C11 defines a global namespace
-// `max_align_t` type.
-//
-// To be certain, we consider every non-void fundamental type specified by the
-// standard. On most platforms `long double` would be enough, but iOS 32-bit
-// has an 8-byte aligned `double` and `long long int` and a 4-byte aligned
-// `long double`.
-//
-// So far we've covered locals and other non-allocated storage, but we also need
-// confidence that allocated storage from `malloc`, `new`, etc will also be
-// suitable for objects with this alignment reuirement.
-//
-// Apple document that their implementation of malloc will issue 16-byte
-// granularity chunks for small allocations (large allocations are page-size
-// granularity and page-aligned). We think that allocated storage will be
-// suitable for these objects based on the following assumptions:
-//
-// 1. 16-byte granularity also means 16-byte aligned.
-// 2. `new` and other allocators follow the `malloc` rules.
-//
-// We also have some anecdotal evidence: we don't see lots of misaligned-storage
-// crashes on 32-bit iOS apps that use `double`.
-//
-// Apple's allocation reference: http://bit.ly/malloc-small
-struct alignas(max_align_v) max_align_t {};
-