Function portable_path 

pub fn portable_path(file: &str) -> String

Render a source path with / separators on every platform. 在任何平台上都以 / 分隔符渲染源码路径。

file!() records the platform separator, and a declaration cannot rewrite it at compile time without allocating, so the portable form is produced when a path is displayed or compared instead. Identity is unaffected: hashing folds both separators to the same byte. file!() 记录平台分隔符，而声明在编译期无法在不分配的前提下改写它，因此改为 在显示或比较时产出可移植形式。身份不受影响：哈希会把两种分隔符折叠为同一字节。