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在std::array中，我们可以简单地这样表述

std::array<std::array<char,10>, 2> arr_gcc{ 
    "abcdefghi", "abcdefghi"
};

或者甚至在与 -Wall 一起铿锵声中，它们只需要更明确的表达，必须添加更多像这样的子对象大括号

std::array<std::array<char,10>, 2> arr_clang_wall_favor{{
    {"abcdefghi"}, {"abcdefghi"}
}};

说到std::vector, 一种方法是像他的一样显式地构造每个子对象。

// This works in both clang and gcc
std::vector vec{
    std::array<char,10>{"abcdefghi"}, std::array<char,10>{"abcdefghi"}
};

如果我们尝试像这样汇总

std::vector<std::array<char,10> > vec_clang{{
    {"abcdefghi"}, {"abcdefghi"}
}};

它仅在clang中有效，但在gcc中是错误的

<source>: In function 'int main()':
<source>:21:6: error: no matching function for call to 'std::vector<std::array<char, 10>, std::allocator<std::array<char, 10> > >::vector(<brace-enclosed initializer list>)'
     }};
      ^
In file included from /opt/compiler-explorer/gcc-7.3.0/include/c++/7.3.0/vector:64:0,
                 from <source>:2:
/opt/compiler-explorer/gcc-7.3.0/include/c++/7.3.0/bits/stl_vector.h:411:2: note: candidate: template<class _InputIterator, class> std::vector<_Tp, _Alloc>::vector(_InputIterator, _InputIterator, const allocator_type&)
  vector(_InputIterator __first, _InputIterator __last,
  ^~~~~~
/opt/compiler-explorer/gcc-7.3.0/include/c++/7.3.0/bits/stl_vector.h:411:2: note:   template argument deduction/substitution failed:
<source>:21:6: note:   candidate expects 3 arguments, 1 provided
     }};
      ^

std::vector和之间是否存在聚合初始化差异std::array？如果是，为什么？

按照标准，gcc 是否应该像 clang 那样编译该聚合？

godbolt.org/g/TRZHnu

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