![c++ - literal class compile error with constexpr constructor and function (differ vc, g++) - Stack Overflow c++ - literal class compile error with constexpr constructor and function (differ vc, g++) - Stack Overflow](https://i.stack.imgur.com/ByQQ7.png)
c++ - literal class compile error with constexpr constructor and function (differ vc, g++) - Stack Overflow
map_field.h:332:37: error: constexpr constructor never produces a constant expression [-Winvalid-constexpr] · Issue #8150 · protocolbuffers/protobuf · GitHub
![c++ - literal class compile error with constexpr constructor and function (differ vc, g++) - Stack Overflow c++ - literal class compile error with constexpr constructor and function (differ vc, g++) - Stack Overflow](https://i.stack.imgur.com/cX6Em.png)