[Emacs-diffs] emacs-26 e5471b2: Add commentary for subtle aspect of frame.el

[Eli Zaretskii]

branch: emacs-26
commit e5471b2381e885d5d214bfa09ab0c35275fc6048
Author: Eli Zaretskii <address@hidden>
Commit: Eli Zaretskii <address@hidden>

    Add commentary for subtle aspect of frame.el
    
    * lisp/frame.el: Explain why we use symbol-function when adding
    watchers for certain variables that need to trigger redisplay.
---
 lisp/frame.el | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lisp/frame.el b/lisp/frame.el
index 447413b..29c31f4 100644
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -2475,6 +2475,9 @@ See also `toggle-frame-maximized'."
 ;; F5 then produces the correct effect, the variable doesn't need
 ;; to be in this list; otherwise, it does.
 (mapc (lambda (var)
+        ;; Using symbol-function here tells the watcher machinery to
+        ;; call the C function set-buffer-redisplay directly, thus
+        ;; avoiding a potential GC.
         (add-variable-watcher var (symbol-function 'set-buffer-redisplay)))
       '(line-spacing
         overline-margin