GCC目录选项 - 系统 [英] GCC directory option -isystem

问题描述

通过此链接： http://gcc.gnu.org/onlinedocs/gcc/Directory-Options .html

如果标准系统包含
目录，或者使用-isystem指定
的目录，也用
-I指定，-I选项将被忽略。该目录仍然会被搜索，但
作为系统目录，位于系统包含的正常
位置。

<

$ / $>
$ b

  [14:45:37 Wed Apr 27]〜/ junkPrograms / src $ gcc hello.c -isystem -I ../include/ 
 ../include/：file not recognized：is a directory 
 collect2：ld returned 1 exit status 
 [14:45： 〜/ junkPrograms / src $ gcc hello.c -I isystem ../include/ 
 ../include/：文件不被识别：是一个目录
 collect2：ld返回1个出口状态
 [14:45:57 Wed Apr 27]〜/ junkPrograms / src 
  

这是否意味着如果连接了 -isystem ，那么dir将被赋予正常系统目录的优先权？

解决方案

文档说：

-isystem dir

在由-I指定的所有目录之后但在标准系统目录之前搜索头文件的目录。将其标记为系统目录，以便获得与应用于标准系统目录相同的特殊待遇。如果dir以=开头，那么=将被sysroot前缀替换;请参阅--sysroot和-isysroot。

所以你错了。你需要为-isystem选项本身指定一个目录，它不像你似乎在尝试的-I选项的修饰符那样工作。

我相信你的命令应该是：

  $ gcc -isystem ../include hello.c 
  

From this link: http://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html

If a standard system include directory, or a directory specified with -isystem, is also specified with -I, the -I option will be ignored. The directory will still be searched but as a system directory at its normal position in the system include chain.

What is the way to run this?

[14:45:37 Wed Apr 27] ~/junkPrograms/src  $gcc hello.c -isystem -I ../include/
../include/: file not recognized: Is a directory
collect2: ld returned 1 exit status
[14:45:42 Wed Apr 27] ~/junkPrograms/src  $gcc hello.c -I isystem ../include/
../include/: file not recognized: Is a directory
collect2: ld returned 1 exit status
[14:45:57 Wed Apr 27] ~/junkPrograms/src  $

and does this mean that if -isystem is attached, the dir will be given the precedence of a normal system dir?

解决方案

The documentation says:

-isystem dir

Search dir for header files, after all directories specified by -I but before the standard system directories. Mark it as a system directory, so that it gets the same special treatment as is applied to the standard system directories. If dir begins with =, then the = will be replaced by the sysroot prefix; see --sysroot and -isysroot.

So you're using it wrong. You need to specify a directory for the -isystem option itself, it doesn't work like a "modifier" of the -I option like you seem to be trying.

I believe your command should be:

$ gcc -isystem ../include hello.c

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