Recently I found there was error messages when I open C/C++ files in Vim (see the following photo).
So I googled, and installed so-called libclang-dev. After the installation, the error message became more terrible:
Fortunately, I spotted a thread of clang_complete in GitHub, and the author's comment was the solution for me.
I must had installed the clang_complete manually and then it has been installed again by Vundle. :-p
Other useful link found during the search:
clang_complete can be configured to use the clang executable or the clang library