下面这段配置是对代码中的tab缩进做的优化，从CSDN上抄来的，感觉挺好。 但是用上它以后，我打开.c文件后 helm-gtags-mode不会自动打开 helm-gtags 已经添加hook 到c-mode上。把下面的注释掉，打开.c .h文件后helm-gtags-mode就会自动加载。 大神帮忙瞅瞅这是什么原因。
另外，平时打开.c文件是显示的是C/l mode 加上下面的配置以后就显示C/lah mode。
(setq indent-tabs-mode nil)
(setq default-tab-width 4)
(setq tab-width 4)
(setq tab-stop-list ())
(loop for x downfrom 40 to 1 do
(setq tab-stop-list (cons (* x 4) tab-stop-list)))
(defconst my-c-style
'((c-tab-always-indent . t)
(c-comment-only-line-offset . 4)
(c-hanging-braces-alist . ((substatement-open after)
(brace-list-open)))
(c-hanging-colons-alist . ((member-init-intro before)
(inher-intro)
(case-label after)
(label after)
(access-label after)))
(c-cleanup-list . (scope-operator
empty-defun-braces
defun-close-semi))
(c-offsets-alist . ((arglist-close . c-lineup-arglist)
(substatement-open . 0)
(case-label . 4)
(block-open . 0)
(knr-argdecl-intro . -)))
(c-echo-syntactic-information-p . t)
)
"My C Programming Style")
;; offset customizations not in my-c-style
(setq c-offsets-alist '((member-init-intro . ++)))
;; Customizations for all modes in CC Mode.
(defun my-c-mode-common-hook ()
;; add my personal style and set it for the current buffer
(c-add-style "PERSONAL" my-c-style t)
;; other customizations
(setq tab-width 4
;; this will make sure spaces are used instead of tabs
indent-tabs-mode nil)
;; we like auto-newline and hungry-delete
(c-toggle-auto-hungry-state 1)
;; key bindings for all supported languages. We can put these in
;; c-mode-base-map because c-mode-map, c++-mode-map, objc-mode-map,
;; java-mode-map, idl-mode-map, and pike-mode-map inherit from it.
(define-key c-mode-base-map "/C-m" 'c-context-line-break)
)
(add-hook 'c-mode-common-hook 'my-c-mode-common-hook)