bug#66113: Apply the entire diff buffer

[Dmitry Gutov <dmitry@gutov.dev>]

On 23/09/2023 20:52, Juri Linkov wrote:
> +(defun diff-apply-buffer ()
> +  "Apply the diff in the entire diff buffer.
> +When applying all hunks was successful, then save the changed buffers."
> +  (interactive)
> +  (let ((buffer-edits nil)
> +        (failures 0)
> +        (diff-refine nil))
> +    (save-excursion
> +      (goto-char (point-min))
> +      (diff-beginning-of-hunk t)
> +      (while (pcase-let ((`(,buf ,line-offset ,pos ,_src ,dst ,switched)
> +                          (diff-find-source-location nil nil)))
> +               (cond ((and line-offset (not switched))
> +                      (push (cons pos dst)
> +                            (alist-get buf buffer-edits)))
> +                     (t (setq failures (1+ failures))))
> +               (not (or (eq (prog1 (point) (diff-hunk-next)) (point))
> +                        (eobp))))))
> +    (cond ((zerop failures)
> +           (dolist (buf-edits (reverse buffer-edits))
> +             (with-current-buffer (car buf-edits)
> +               (dolist (edit (cdr buf-edits))
> +                 (let ((pos (car edit))
> +                       (dst (cdr edit))
> +                       (inhibit-read-only t))
> +                   (goto-char (car pos))
> +                   (delete-region (car pos) (cdr pos))
> +                   (insert (car dst))))
> +               (save-buffer)))
> +           (message "Saved %d buffers" (length buffer-edits)))
> +          (t
> +           (message "%d hunks failed; no buffers changed" failures)))))

Sorry, was there supposed to be a call to diff-test-hunk here? Or I'm 
just not following the implementation.

I tried testing it out too. There is a patch where the third hunk 
doesn't apply (errors with "can't find the text to patch" in regular 
usage). This command ends with cryptic "No next hunk".