Why does initialization of array of pairs still need double braces in C++14?

Question

With the C++14 standard, the initialization of an std::array can go with single braces (see http://en.cppreference.com/w/cpp/container/array):

This, however

Answer 1

The C++14 brace elision rule applies only to subaggregate initialization.

So for example something like this works:

std::array, 3> a{1, 11, 2, 22, 3, 33};

Here an aggregate of aggregates can be list-initialized without extra braces.

But std::pair is not an aggregate (it has constructors), so the rule does not apply.

Which means that without the brace elision rule, std::array, itself being an aggregate with an array inside, needs an extra set of braces in order to be list-initialized. Remember that the class template array is implemented as:

template 
struct array {
  T elems[N];
};

To list-initialize it without the brace elision rule, you need an extra set of braces to get to the elems member.