bug#42110: Whitespace Newline Face Doesn't Disappear

["Basil L. Contovounesios" <contovob@tcd.ie>]

found 37467 25.3
forcemerge 37467 42110
quit

> From: Robin Choudhury <robin_choudhury1@protonmail.com>
> To: bug-gnu-emacs@gnu.org
> Subject: 26.3; Whitespace Newline Face Doesn't Disappear
> -----
>
> When typing at the bottom of a document, a newline is inserted. An
> additional newline is then inserted. Upon insertion, a face higlights
> the first newline's emptiness. Typing in the second newline should make
> this face disappear. However, it remains.

Thanks, I can reproduce this in Emacs versions 25.3-28 inclusive, but
not in 24.5.  I think this is a duplicate of bug#37467, and sounds like
it might be related/due to bug#24745; CCing Reuben.

Some minor notes on your configuration:

> The whitespace configuration (13.2.2):
> (use-package whitespace
>   :ensure t
    ^^^^^^^^^
No need for this, lisp/whitespace.el is built-in.

>   :init
>   (setq prelude-whitespace nil)
>   (setq whitespace-line-column 80)
>   ;; Highlight trailing whitespace
>   (setq whitespace-style
>         ;; There's a bug in empty where the face doesn't go away after
>         ;; typing below the newline.
>         '(face trailing lines-tail indentation::space tab-mark empty))
>   :config
>   (global-whitespace-mode t))
                           ^^^
No well behaved mode function documents t as a valid argument for
enabling it.  Instead, you should write one of the following or
equivalent:

  (global-whitespace-mode)
  (global-whitespace-mode 1)

Here's a simpler reproduction recipe:

0. emacs -Q
1. C-o
2. (progn (setq whitespace-style '(face empty))
          (whitespace-mode))
3. C-x C-e
4. C-m C-m
5. asd

Expected: the yellow highlight on the empty line 6 disappears, since
line 6 is not at EOB any longer.

Observed: the empty line 6 is still highlighted with the
whitespace-empty face.

Thanks,

-- 
Basil