a clang error

[tolerious]

like this

[redguardtoo]

That's normal. You know how to use clang, right? To make the clang auto-complete work, you need tell clang the directories to search c++ headers. check my project cpputils-cmake for details. That is common for all the C++ IDEs. I mean you need set up directories for C/C++ headers even you are using "Modern" IDEs (Visual Studio, QtCreator, Eclipse ...)

[redguardtoo]

btw, what software u use to create gif?

[tolerious]

OK,I will check out it,I use byzanz to generate a gif.

[dgutov]

FWIW, I've just typed this example in, and I don't see the error. And company-clang-arguments is nil.
After I type the beginning of that name, I get offered two completions: sockaddr and sockaddr_storage. If I then finish it with _in and try to complete, it just says "No completion found".

$ clang --version
Ubuntu clang version 3.0-6ubuntu3 (tags/RELEASE_30/final) (based on LLVM 3.0)
Target: x86_64-pc-linux-gnu
Thread model: posix