CC mode: make Tab just insert one tab or complete, no auto-indenting

Question

I am dissatisfied with current behaviour of Emacs in CC Mode. I'm not sure if this applies to other major modes, but that's one I'm currently struggling with. Here are my problems:

1. When I press tab, instead of inserting just one tab, Emacs either inserts enough space to match last line indentation level.
2. I also can't insert tab when on empty line.

I believe those are caused by c-indent-line-or-region function, according to C-h l, but I don't know what I can do with it. Neither of possible values for c-tab-always-indent change this situation.

I found something about tab-to-tab-stop, and using it helped, however, it disabled expanding snippets from yasnippet or <s in org-mode.

My setup consists of Evil-mode, Company-mode, LSP-mode, and following directives in init.el:

(setq-default indent-tabs-mode t)
(setq tab-width 8)
(defvaralias 'c-basic-offset 'tab-width)

(setq-default c-default-style "linux"
              c-basic-offset 8
              c-tab-always-indent nil
              indent-tabs-mode t)

tab-to-tab-stop has something related to expanding in it's source:

  (and abbrev-mode (= (char-syntax (preceding-char)) ?w)
       (expand-abbrev))

but it doesn't help.

I thought I found solution in using tab-to-tab-stop with c-tab-always-indent to 'complete, and it worked, for some time, but after I restarted emacs, it, again, has no effect.

(setq-default c-tab-always-indent 'complete)
...
;; in configuration for evil mode
(define-key evil-insert-state-map (kbd "TAB") 'tab-to-tab-stop)

So is there a way for me to make tabs stupid, i.e. having pressing Tab just insert \t (or N spaces if configured so), while keeping the ability to expand snippets using it?

EDIT: After disabling tab-to-tab-stop and seeing with C-h l what exactly causes snippets to expand (org-cycle and yas-expand), I'm starting to suspect that there is some kind of function that tries to understand the context and apply specific action, and my evil-state map interferes with it, taking priority or something? Are my guesses wrong?

Answer 1

If your goal is to insert a tab character, you can use C-q <tab>, and let the default binding for tab key as is.

With C-q you invoke quoted-insert, so the next key is not interpreted as a command, but inserted "verbatim" in the buffer.

C-q is also useful in other contexts. For example, to search for tabs character you can type C-s C-q <tab>.

Answer 2

(setq-default c-tab-always-indent 'complete)

...

;; don't do this:
;; (define-key evil-insert-state-map (kbd "TAB") 'tab-to-tab-stop)

;; also don' this:
;; (global-set-key (kbd "TAB") 'tab-to-tab-stop)
;; (global-set-key [tab] 'tab-to-tab-stop)

;; do this
(define-key c-mode-base-map (kbd "<tab>") 'tab-to-tab-stop)
(define-key c-mode-base-map [tab] 'tab-to-tab-stop)