Linux _GNU_SOURCE 和 __USE_GNU
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_GNU_SOURCE and __USE_GNU
提问by Foo Bah
I want to use CPU_SET, which is a glibc linux-specific macro that should be defined in sched.hThe manpage clearly states that _GNU_SOURCEmust be defined so that the macro is defined. However, looking at the header, CPU_SETis defined only if __USE_GNUis defined (there is an #ifdefguard). I seem to remember a few years ago that _GNU_SOURCEwas needed.
我想使用CPU_SET，这是一个 glibc linux 特定的宏，应该在sched.h联机帮助页中明确指出_GNU_SOURCE必须定义，以便定义宏。但是，查看标题，CPU_SET仅在定义时才__USE_GNU定义（有#ifdef保护）。我好像记得几年前那_GNU_SOURCE是需要的。
Questions:
问题：
1) Clearly the manpage is off. How do I notify the maintainer that the manpage is incorrect?
1) 显然，联机帮助页已关闭。如何通知维护人员联机帮助页不正确？
2) When did the transition from _GNU_SOURCEto __USE_GNUhappen (either in terms of version or time)
2）什么时候从_GNU_SOURCE到__USE_GNU发生的转变（无论是版本还是时间）
3) Are there circumstances where newer versions of glibc still use _GNU_SOURCE? Or can I safely assume that defining __USE_GNUis sufficient?
3) 是否存在较新版本的 glibc 仍在使用的情况_GNU_SOURCE？或者我可以安全地假设定义__USE_GNU就足够了？
采纳答案by R.. GitHub STOP HELPING ICE
_GNU_SOURCEis the only one you should ever define yourself. __USE_GNUis defined internally through a mechanism in features.h(which is included by all other glibc headers) when _GNU_SOURCEis defined, and possibly under other conditions. Defining or undefining __USE_GNUyourself will badly break the glibc headers.
_GNU_SOURCE是您唯一应该定义自己的人。__USE_GNU在定义features.h时_GNU_SOURCE（可能在其他条件下）通过 in （所有其他 glibc 头文件中包含的机制）在内部定义。定义或取消定义__USE_GNU自己会严重破坏 glibc 头文件。
回答by Giuseppe Scrivano
you have to define_GNU_SOURCE before anything else. This snippet works here:
你必须先定义_GNU_SOURCE。这个片段在这里工作：
#define _GNU_SOURCE
#include <sched.h>
int main()
{
cpu_set_t set;
CPU_SET(0, &set);
return 0;
}
