rust - Rust 中的 extern fn 和 extern "C"fn 有什么区别？

Question

我曾尝试阅读各种 github 问题，试图找出其中的区别，结果却一头雾水。

#[no_mangle]
pub extern fn foo() {
   ...
}

对比

#[no_mangle]
pub extern "C" fn foo() {
   ...
}

Answer 1

没有区别因为，as the reference说:

By default external blocks assume that the library they are calling uses the standard C ABI on the specific platform.

extern "C" -- This is the same as extern fn foo(); whatever the default your C compiler supports.

安issue创建时总是要求明确声明 extern "C" 但 RFC has been refused .

有一个issue在 fmt-rfcs关于“我们应该将 extern "C"fn 格式化为那个还是 extern fn？”。