ggtags-fontify-code conflicts with hl-line-mode

[mohkale]

See here.

Whenever ggtags looks up a tag and highlights it with ggtags-fontify-code the active hl-line in the original buffer is removed. I've narrowed the issue down to ggtags-fontify-code after some trial debugging.

Doing (advice-add 'ggtags-fontify-code :override #'identity) fixes the issue for now (but removes tag highlighting 😢.

You need to set (setq hl-line-sticky-flag nil) to get this bug to appear.

[mohkale]

I really think emacs needs better support for just highlighting an arbitrary string. Different packages keep re-implementing this and none really reach the same quality as just writing them into a buffer and running font-lock on it.

Personally I think org-mode src block highlighting is the best. It even supports tree-sitter faces which makes the highlighted code identical to if I had just written it out myslef.

Here's a way to make ggtags use org for syntax highlighting. It should work reasonably well until we find a better implementation for ggtags itself.

(require 'org-src)

(defun ggtags-fontify-code-with-org+ (code &optional mode)
  (or mode (setq mode major-mode))
  (if (stringp code)
      (let* ((lang (s-chop-suffix "-mode" (symbol-name mode)))
             ;; Fallback to default-face not org-block-face.
             (org-src-block-faces `((,lang . (default)))))
        (with-temp-buffer
          (insert code)
          (org-src-font-lock-fontify-block lang (point-min) (point-max))
          (buffer-substring (point-min) (point-max))))
    code))

(advice-add #'ggtags-fontify-code :override #'ggtags-fontify-code-with-org+)