Error: initializer must be brace-enclosed

Question

这个错误是什么意思，为什么我不能用花括号初始化列表初始化这个结构？不幸的是，结构是自动生成的。

// Contains no functionality, purely documentative.
struct NativeTable {};

...

struct TableKeyT : public flatbuffers::NativeTable {
  typedef TableKey TableType;
  std::string exp{};
  std::string type{};
  std::string ext{};
};

...

TableKeyT key { std::string(sym), std::string(ex), std::string("") };

[build] ../../../src/io/socket.cpp:102:39: error: initializer for ‘flatbuffers::NativeTable’ must be brace-enclosed
[build]   102 | TableKeyT key { std::string(sym), std::string(ex), std::string("") };
[build]       |           ^~~

Answer 1

由于TableKeyT继承了NativeTable，你还需要初始化基class，但由于它是一个空的class，所以使用{}应该没事。

TableKeyT key { {}, std::string(sym), std::string(ex), std::string("") };
             //^^^

Error: initializer must be brace-enclosed

Error: initializer must be brace-enclosed

c++

gcc

c++20