I’m working on a small Chinese text parser plugin for MySQL 5.6, I’ll write another blog post about it.

The problem that made me to write this blog post, is quite a simple one.

Since I’m working on the Chinese text parser, I need a Chinese tokenizer library, and written in C.

I choosed Libmmseg, as stated above, I’ll write about it in another blog post.

I tried to write a small application using libmmseg, and made it compiled on my MBP.

Then, I need to transfer the application to a linux system(CentOS 6.5) and make it compile again.

Then, I got the problem.

The problem is something like this:

/tmp/ccsP9If4.o: In function `segment(char const*, css::Segmenter*)':
mmseg_test.cc:(.text+0x1af): undefined reference to `css::Segmenter::setBuffer(unsigned char*, unsigned int)'
mmseg_test.cc:(.text+0x1e6): undefined reference to `css::Segmenter::peekToken(unsigned short&, unsigned short&, unsigned short)'
mmseg_test.cc:(.text+0x207): undefined reference to `css::Segmenter::popToken(unsigned short, unsigned short)'
mmseg_test.cc:(.text+0x267): undefined reference to `css::Segmenter::peekToken(unsigned short&, unsigned short&, unsigned short)'
mmseg_test.cc:(.text+0x2af): undefined reference to `css::Segmenter::popToken(unsigned short, unsigned short)'
mmseg_test.cc:(.text+0x30b): undefined reference to `css::Segmenter::thesaurus(char const*, unsigned short)'

That’s quite strange, since I have compile the libmmseg and install it to /usr/local/lib, and added the dependency, but the ld still can’t find the library…… WTF!!!!

I tried lots of the ways, I even compile and try to link the objects by hand, and still can’t be done.

I’m frastrated.

Then I see this.

It said:

The trick here is to put the library AFTER the module you are compiling. The problem is a reference thing. The linker resolves references in order, so when the library is BEFORE the module being compiled, the linker gets confused and does not think that any of the functions in the library are needed. By putting the library AFTER the module, the references to the library in the module are resolved by the linker.

This saved my life!!!!

So, this is the reason I wrote this small blog post, the God D*mned GCC!!!!! Why it is so stupid like this when llvm can handle this beautifully?

I suddenly get understand why Apple give up it and using llvm instead, sure, I’ll try to use llvm myself instead of gcc too.

Sorry RMS and GNU.