[PATCH 2/2] libstdc++: Add std::aligned_union.

[Jonathan Wakely]

On 16/04/14 17:06 +0200, Rüdiger Sonderfeld wrote:
>C++11: [meta.trans.other]
>
>* libstdc++-v3/testsuite/20_util/aligned_union/1.cc: New file.
>* libstdc++-v3/include/std/type_traits (__strictest_alignment): New
>  helper struct.
>  (aligned_union): New struct (C++11).
>  (aligned_union_t): New type alias (C++14).

Thanks! I was hoping to implement it the straightforward way, but was
thwarted by http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59012


>+  template <typename... _Types>
>+    struct __strictest_alignment
>+    {
>+      static const size_t _M_alignment = 0;
>+      static const size_t _M_size = 0;

The naming convention is to use _S_xxx for static members

>+  template <size_t Len, class... Types>
>+    using aligned_union_t = typename aligned_union<Len,Types...>::type;

It should be s/class/typename/ here.

Is <initializer_list> needed for the testcase?

The testcase can use { dg-do compile } to turn it into a compile-only
test, and then doesn't need a main() function.

Otherwise I think this looks good, thanks.