Rust 条件编译属性覆盖了多少行? [英] How many lines are covered by the Rust conditional compilation attribute?

问题描述

我正在尝试使用条件编译语句.除了定义一个只应存在于调试版本中的函数之外，我想定义一组仅存在于调试版本中的变量/常量/类型.

I'm trying to use a conditional compilation statement. Beyond defining a function that should only exist in a debug build, I want to define a set of variables/constants/types that only exist in the debug build.

#[cfg(debug)]
pub type A = B;
pub type B = W;

#[cfg(other_option)]
pub type A = Z;
pub type B = I;
let test = 23i32;

在这种情况下，条件编译属性实际上覆盖"了多少行?它只有一个(在这种情况下我会期望什么)?有没有办法确保整个代码块(包括变量、类型和两个函数)都被条件覆盖?

How many lines are actually "covered" by the conditional compile attribute in this case? Is it only one (what I would expect in this context)? Are there ways to ensure that a whole block of code (including variables, types and two functions) is covered by the condition?

推荐答案

一个 #[attribute] 只适用于下一个 item.请参阅 Rust 手册.

An #[attribute] only applies to the next item. Please see the Rust book.

编辑:我认为目前不可能在任意数量的声明中传播一个属性.

Edit: I don't think it is currently possible to spread an attribute over an arbitrary number of declarations.

有关属性及其应用的其他深入信息可以在 Rust 参考.

Additional, in-depth information on attributes and their application can be found at Rust reference.

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