gcc预编译头文件:pragma出现在主文件中 [英] gcc precompiled header: pragma once in main file

问题描述

我创建了头文件.简单一些如下.

I created a header file. Something simple as follows.

#pragma once

#include <iostream>

template<typename T>
void say(T t) {
    std::cout << t << std::endl;
}

，然后使用g++和g++ hello.h创建gch预编译头.它给了我这个警告->

and then use g++ to create the gch pre-compiled header with g++ hello.h. It gives me this warning ->

pch.h:2:9: warning: #pragma once in main file
    2 | #pragma once
      |         ^~~~

但是创建的gch文件和预编译的头文件可以正常工作.如果使用标题保护，则该错误消失.

But the gch file created and the pre-compiled header works fine. This error goes away if I use header guards.

我在这里做错什么了吗?

Am I doing something wrong here?

推荐答案

您没有做错任何事情；这是一种实施质量问题，之前在问题跟踪器中已经提到 (但是据我所知，目前尚无改变行为的计划).

You're not doing anything wrong; this is a quality of implementation issue that has been mentioned on the issue tracker before (but, to my knowledge, there are currently no plans to change the behaviour).

在Clang中，您可以针对特定的编译器调用(使用-Wno-pragma-once-outside-header)关闭警告；在GCC中，您现在只需要咧着嘴笑着忍着.

In Clang, you could turn off the warning for that particular compiler invocation (with -Wno-pragma-once-outside-header); in GCC you'll just have to grin and bear it for now.

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