stdatomic.h not found, for use in swift & metal compute shader

问题

I'm trying to use a struct with an atomic_int for use in a metal compute shader. However, it says I need to import #include "stdatomic.h" - but every time I try, it can't find the file.

#include "stdatomic.h" // 'stdatomic.h' file not found

I'm trying to build my application for macOS Catalina

struct Fitness {
    atomic_int weight; // Declaration of 'atomic_int' must be imported from module 'Darwin.C.stdatomic' before it is required
    ...others...
};

• I have tried placing a copy of stdatomic.h into my project, but that gives a lot of compilation errors.
• My struct is defined in a .h header file.
• The struct is used by both Swift & Metal.
• I'm using XCode 11.4.

Update: If I #include in a .cpp file it works...why not a header?

Any ideas what is wrong? Can I not do what I want?

来源：https://stackoverflow.com/questions/61001742/stdatomic-h-not-found-for-use-in-swift-metal-compute-shader