尝试过好多代码补全插件，目前找到一款用着比较满意的，前端用company，后端主要用irony，基本上对于C/C++项目来说使用体验非常好，其他语言的未体验过。
下面是主要配置，一些插件可能需要emacs版本 >= 25.1
1 ;; 代码补全的配置 2 ;; =================================================== 3 (require 'company) 4 (require 'irony) 5 (require 'company-irony) 6 (add-hook 'c++-mode-hook 'company-mode) 7 (add-hook 'c-mode-hook 'company-mode) 8 (add-hook 'c++-mode-hook 'irony-mode) 9 (add-hook 'c-mode-hook 'irony-mode) 10 (add-hook 'irony-mode-hook 'irony-cdb-autosetup-compile-options) 11 (setq company-idle-delay 0) 12 (setq company-minimum-prefix-length 2) 13 (setq company-dabbrev-downcase nil) 14 (add-to-list 'company-backends 'company-dabbrev) 15 (add-to-list 'company-backends 'company-dabbrev-code) 16 (add-to-list 'company-backends 'company-files) 17 (add-to-list 'company-backends 'company-semantic) 18 (add-to-list 'company-backends 'company-keywords) 19 (add-to-list 'company-backends 'company-irony) 20 ;;(add-to-list 'company-backends 'company-gtags) 21 (add-to-list 'company-backends 'company-capf) 22 (require 'company-c-headers) 23 (add-to-list 'company-c-headers-path-system "/usr/include/c++/4.9.2/") 24 (add-to-list 'company-backends 'company-c-headers) 25 (global-set-key (kbd "C-;") 'company-complete-common) 26 ;;使用M-n 和 M-p 选择候选项 27 ;;company 颜色设置 28 (defun theme-dark () 29 (interactive) 30 (set-face-foreground 'company-tooltip "#000") 31 (set-face-background 'company-tooltip "#fff") 32 (set-face-foreground 'company-scrollbar-bg "#fff") 33 (set-face-background 'company-scrollbar-fg "#999") 34 ) 35 (theme-dark)
对于Irony的话，需要在emacs中手动执行 M-x irony-install-server 来安装好irony的后端server。
另外有了irony和company-c-headers之后，如果你用的是一个大型项目，那么company-gtags就不需要了，因为company-gtags会使得大型项目下company的提升项居多，貌似是将当前项目所有的符号都作为备选了（也可能是我没配置对）。
参考：