在#include语句中使用垃圾字符时没有编译器错误 [英] No compiler error on using garbage characters in #include statement

问题描述

#include <iostream> gfhgfhgf
using namespace std;

int main() {
    return 0;
}

为什么这段代码会编译？根据包含语法的gcc参考：

Why does this code snippet compile? As per The gcc reference on Include Syntax:

如果文件名后面的行上有任何内容（注释除外），则会出错。

It is an error if there is anything (other than comments) on the line after the file name.

$ b

and that's exactly what's being done in the code.

推荐答案

使用 -pedantic在 gcc 和 clang 中的-errors 标志将此转换为错误查看活动：

Using the -pedantic-errors flags in gcc and clang turns this into an error see it live:

error: extra tokens at end of #include directive
#include <iostream> gfhgfhgf
                    ^

这表示它是扩展名。

如果我们查看接口C和TAL In他们有一些这样的代码：

If we look at the Interfacing C and TAL In The Tandem Environment they have some code like this:

#include <stdlibh> nolist
                   ^^^^^^

因此， gcc 和 clang 支持include指令后的额外字符，以支持某些平台所需的扩展。使用附加标志可使 gcc 和 clang 对违反标准的扩展发出警告，如上所述，您可以使用 -pendatic-errors 将此转换为错误（强调我）：

So both gcc and clang support extra characters after the include directive to support an extension needed on some platforms. Using the -pedantic flags makes gcc and clang produce a warning for extensions that violate the standard and as noted above you can use -pendatic-errors to turn this into an error (emphasis mine):

到获取所需的所有诊断按标准，您应该
也指定-pedantic（或-pedantic错误，如果你想他们是
错误，而不是警告）。

to obtain all the diagnostics required by the standard, you should also specify -pedantic (or -pedantic-errors if you want them to be errors rather than warnings).

我们可以在 nolist 扩展名的引用。 hp.com/hpsc/doc/public/display?docId=emr_na-c02128447rel =nofollow>针对NonStop Systrms的HP'sC / C ++程序员指南，其中说：

We can find a reference for the nolist extension in the HP'sC/C++ Programmers guide for NonStop Systrms which says:

nolist
  directs the compiler not to list the contents of the file or sections
  being included.
This is an HP NonStop  extension to the standard.

注意，草案C ++标准定义此形式 include的语法include 部分中：

Note, the draft C++ standard defines the grammar for this form of include in section 16.2 [cpp.include] as follows:

# include < h-char-sequence> new-line

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