Fix: the guard-lf-intact-major-modes where not taken into account

[abougouffa]

This PR fixes the issue mentioned below:

While trying to add some modes (like pcap-mode) to guard-lf-intact-major-modes, I've noticed that it wasn't taken into account and that the mode was always changed to fundamental-mode.

After a quick check, it turned out that guard-lf-intact-major-modes wasn't used correctly in provided-mode-derived-p, which needs the modes (&rest modes) to be provided as separate arguments and not as a list.

The signature of the function:

(provided-mode-derived-p MODE &rest MODES)

[jcs090218]

How about?

(defun guard-lf--set-auto-mode-0 (fnc &rest args)
  "Advice around the function `set-auto-mode-0'.

Arguments FNC and ARGS are used to call original operations."
  (when guard-lf--detect-large-file
    (setq guard-lf--detect-large-file nil)  ; Revert back to `nil'
    (when (and guard-lf-major-mode
-               (not (provided-mode-derived-p (nth 0 args) guard-lf-intact-major-modes)))
+               (not (derived-mode-p (nth 0 args) guard-lf-intact-major-modes)))
      (message "[INFO] Large file detected; use the `%s' as the new major mode"
               guard-lf-major-mode)
      (setf (nth 0 args) guard-lf-major-mode)))
  (apply fnc args))

[abougouffa]

Well, it won't work for two reasons:

1. derived-mode-p has also a definition similar to provided-derived-mode-p, it requires several arguments, not a list:

(derived-mode-p 'c-mode 'c++-mode 'python-mode) ;; Correct => it returns t if the current's buffer `major-mode` is derived from c-mode, c++-mode or python-mode

(derived-mode-p '(c-mode c++-mode 'python-mode)) ;; Incorrect => returns (almost) always nil

2. derived-mode-p is just a convenient function around provided-derived-mode-p, it compares the current major-mode to the other modes, so:

(provided-derived-mode-p major-mode 'c-mode 'c++-mode 'python-mode)

;; Is equivalent to:

(derived-mode-p 'c-mode 'c++-mode 'python-mode)

So, even if we want to use derived-mode-p (which we don't want since at set-auto-mode-0, the major-mode isn't detected yet, we need to do it with an (apply #'derived-mode-p (append (car args) guard-lf-intact-major-modes))

The apply function takes a function and a list of arguments, and use them as arguments to to call the function, so:

(apply #'+ '(1 2 3 4 5)) ; => 15

;; Is equivalent to:

(+ 1 2 3 4 5) ; => 15

While, doing:

(setq l1 '(1 2)
      l2 '(2 3 4 5))

(+ (car l1) l2) ; which is equivalent to what we have now in the code

Is not a valid Elisp expression

[abougouffa]

You can set up a test like this:

• Set the limit:

(setq large-file-warning-threshold 10000) ; 10k

• C-x C-f and open a .c file larger than 10k
  • The file should be opened by guard-lf in fundamental-mode
• Kill the 10k file buffer
• Run this:

(add-to-list 'guard-lf-intact-major-modes 'c-mode)
(add-to-list 'guard-lf-intact-major-modes 'c-ts-mode)

• C-x C-f open the 10k .c file
  • It will be opened in fundamental-mode, the guard-lf-intact-major-modes is not respected

[jcs090218]

Thank you for your explanation. Sorry, I was a little busy and wasn't paying enough attention to this. 😓

[abougouffa]

Thanks for your responsiveness @jcs090218 !