Question

在std::array中，我们可以简单地说明这个

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

或者即使与-Wall合作，他们只需要更明确的表达，不得不添加更多这样的子对象支撑

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

谈到std::vector，一种方法是像他的

一样明确地构建每个子对象

// 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聚合

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

它仅适用于clang，但在gcc中是一个错误

<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std::array之间是否存在聚合初始化差异？如果是，为什么？

按照标准，gcc应该像clang一样编译聚合吗？

godbolt.org/g/TRZHnu

std :: vector和std :: array之间是否存在聚合初始化差异？

0 个答案: