auto-complete-c-headers just works with C. No result with C++

Question

I installed the auto-complete-c-headers package and added the following in my Emacs configuration file

; start auto-complete with emacs
(require 'auto-complete)
; do default config for auto-complete
(require 'auto-complete-config)
(ac-config-default)
; let's define a function which initializes auto-complete-c-headers and gets called for c/c++ hooks
(defun my:ac-c-header-init ()
(require 'auto-complete-c-headers)
  (add-to-list 'ac-sources 'ac-source-c-headers)
  (add-to-list 'achead:include-directories '"/usr/include/c++/4.8
 /usr/include/x86_64-linux-gnu/c++/4.8
 /usr/include/c++/4.8/backward
 /usr/lib/gcc/x86_64-linux-gnu/4.8/include
 /usr/local/include
 /usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed
 /usr/include/x86_64-linux-gnu
 /usr/include
"))
; now let's call this funcion from c/c++ hooks
(add-hook 'c++-mode-hook 'my:ac-c-header-init)
(add-hook 'c-mode-hook 'my:ac-c-header-init)

I included the directories listed by the command gcc -xc++ -E -v -.

The autocomplete works fine with C header files, but does nothing with the C++ ones.

Answer 1

It looks like you are incorrectly adding the C++ headers to achead:include-directories. Each header should be a separate item in the list, not the Heredoc-like syntax you're using. You are prepending just one string with embedded newlines, which of course does not exist on disk. Instead of:

(require 'auto-complete-c-headers)
  (add-to-list 'ac-sources 'ac-source-c-headers)
  (add-to-list 'achead:include-directories '"/usr/include/c++/4.8
 /usr/include/x86_64-linux-gnu/c++/4.8
 /usr/include/c++/4.8/backward
 /usr/lib/gcc/x86_64-linux-gnu/4.8/include
 /usr/local/include
 /usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed
 /usr/include/x86_64-linux-gnu
 /usr/include
"))

Try this:

(require 'auto-complete-c-headers)
  (add-to-list 'ac-sources 'ac-source-c-headers)
  (setq achead:include-directories
   (append '("/usr/include/c++/4.8"
             "/usr/include/x86_64-linux-gnu/c++/4.8"
             "/usr/include/c++/4.8/backward"
             "/usr/lib/gcc/x86_64-linux-gnu/4.8/include"
             "/usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed"
             "/usr/include/x86_64-linux-gnu")
             achead:include-directories)))

The C header files probably work because by default, the package adds /usr/include and /usr/local/include to achead:include-directories.