Clang_complete not worrking - clang

Question

unfortunately I can't manage to make clang_complete work and I could need your help.
I've already compiled vim 7.4 with python support. Here is the output of vim --version | grep python:
+cryptv +linebreak +python/dyn +viminfo
-cscope +lispindent +python3/dyn +vreplace
I followed this guide: https://vtluug.org/wiki/Clang_Complete
Please note that I've started from a clean installation (i.e. no other plugins and no further entries in my .vimrc (except for those shown in the guide above)).
According to the tutorials I've seen so far everything should be working.
However, if I try to get code completion for the following example nothing happens. If I press <c-x><x-u> I receive the error "completefunc not set".
#include <string>
int main()
{
std::string s;
s.
}
Moreover, I've installed the newest version of clang from source and it in my $PATH.
Is there a way to verify that clang_complete is actually installed?
What might cause this problem?
Any help is much appreciated.

Answer 1

Add
filetype plugin indent on
to your vimrc, its missing from the vimrc snippet in the link. This tells vim to do filetype detection and fire autocommands related to those file types. Without it you won't run the following autocommands.
au FileType c,cpp,objc,objcpp call <SID>ClangCompleteInit()
au FileType c.*,cpp.*,objc.*,objcpp.* call <SID>ClangCompleteInit()
Which probably initalize ClangComplete.