gcc/g++ 参数顺序 [英] gcc/g++ parameter order

问题描述

我刚刚在我的新 ubuntu 12.10 服务器上编译了 chironfs 并收到以下错误:

i just compiled chironfs on my new ubuntu 12.10 server and got the following error:

gcc  -Wall -W -Wmissing-prototypes -g -O2 -DFUSE_USE_VERSION=25 -D_FILE_OFFSET_BITS=64 -I/usr/local/include -g -O2 -lm -lfuse  -o chironfs chironfs.o chiron-conf.o chirondbg.o chironfn.o  
chironfs.o: In function `chiron_init':
/root/chironfs-1.1.1/src/chironfs.c:2000: undefined reference to `pthread_create'
chironfs.o: In function `get_rights_by_name':
/root/chironfs-1.1.1/src/chironfs.c:452: undefined reference to `fuse_get_context'

pthread 错误告诉我缺少 -lpthread，但保险丝错误有点奇怪，因为正在使用 -lfuse

the pthread error tells me that -lpthread is missing, but the fuse error is kinda weird cause -lfuse is being used

我在这里找到了一个解决方案 建议将库放在目标文件之后

i found a solution here which suggests to put libraries after object files

所以我删除了 -lfuse 并在行的最后添加了 -lfuse -lpthread

so i removed -lfuse and added -lfuse -lpthread at the very end of the line

现在它编译没有错误，看起来应该是这样:目标文件之后的库

now it compiles without an error and it seems that this is the way it should be: library after object files

我的问题是:为什么参数顺序与 gcc/ld 相关?我认为 gcc 只是像其他所有应用程序一样解析参数，并且可能会将必要的参数转发给 ld 之类的

my question is: why is the parameter order relevant for gcc/ld? i tought gcc just parses the params like every other application and may forward the necessary params to ld or such

一般来说:任何人都知道 gcc 参数排序的事实或技巧，也许还有一点背景知识关于为什么需要这种方式的信息?

in general: anyone knows facts or tips for gcc parameter ordering and maybe a bit background information about why it is needed this way?

谢谢

推荐答案

对象和库的顺序与链接器有关(在创建可执行文件时由编译器隐式调用).当链接器在从左到右的扫描中发现一个它不知道的名称的使用时，它开始寻找定义从那时起.如果定义通过，它不会记住它以备后用.

The order of objects and libraries is relevant to the linker (called implicitly by the compiler when creating an executable). When the linker, in its left-to-right scan, finds a use of a name it doesn't know about it starts looking for a definition from that point on. If a definition passes by, it doesn't remember it for later use.

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