bug#48936: 27.2; pulse-reset-face and extend attribute of pulse-highligh-face

[Gustavo Barros <gusbrs.2016@gmail.com>]

Hi All,

`pulse-reset-face' in `pulse.el' "resets" the `:extend' attribute of 
`pulse-highlight-face' only when it is called with an argument. This is 
done by:

#+begin_src emacs-lisp
(and face
     (set-face-extend 'pulse-highlight-face
                      (face-extend-p face nil t)))
#+end_src

Considering the role `pulse-highlight-face' plays in the way `pulse' 
works, it would be expected that this resetting should also be done for 
the `:extend' attribute when the function is called without an argument, 
otherwise, that face attribute is left in an arbitrary state when one of 
the `pulse-momentary-highlight-...` user facing functions is called 
without an argument.  That state is "the extend attribute of whatever 
face was last passed as an argument to one of the pulsing functions".

An ECM to reproduce the effects of this is the following.  Start `emacs 
-Q', and set `pulse's default face `:extend' to t.

#+begin_src emacs-lisp
(load-library "pulse")
(set-face-extend 'pulse-highlight-start-face t)
#+end_src

Examination of `pulse-highlight-start-face' with `describe-face' shows 
the attribute in place. And, if we evaluate (make sure it is not the 
last line of the buffer when calling `C-x C-e'):

#+begin_src emacs-lisp
(pulse-momentary-highlight-one-line (point))

#+end_src

And the `:extend' does not work. Now eval:

#+begin_src emacs-lisp
(pulse-momentary-highlight-one-line (point) 'pulse-highlight-start-face)

#+end_src

And the pulse face is indeed extended this time. And then, if we eval 
again:

#+begin_src emacs-lisp
(pulse-momentary-highlight-one-line (point))

#+end_src

Now the extend works for this one.

If we want to "revert" the state, it is enough that we call, for 
example:

#+begin_src emacs-lisp
(pulse-momentary-highlight-one-line (point) 'highlight)

#+end_src

(`hightlight' is the face used for this purpose by 
`flymake-show-diagnostic', but any other face with no `extend' attribute 
called by any other user of `pulse.el' infrastructure would do the 
same).

And now,

#+begin_src emacs-lisp
(pulse-momentary-highlight-one-line (point))

#+end_src

no longer works as expected (again).

My suggested fix is that `pulse-reset-face' do the same for the `extend' 
attribute as it does for `background', namely: if it is called with a 
`face' argument, use the extend attribute of that face; otherwise, use 
the extend attribute of `pulse's default face 
`pulse-highlight-start-face'.

Best regards,
Gustavo.




In GNU Emacs 27.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, 
cairo version 1.16.0)
 of 2021-03-25 built on gusbrs-laptop
Windowing system distributor 'The X.Org Foundation', version 
11.0.12009000
System Description: Linux Mint 20.1

Recent messages:
Loading pulse...done
t
nil
[nil 24768 52127 785690 0.03 pulse-tick 
((11422590749233444063540913557203 . 7036874417766400000000)) nil 
395000]
[nil 24768 52130 912738 0.03 pulse-tick 
((57112953856190749572945063578143 . 35184372088832000000000)) nil 
808000]
[nil 24768 52132 913706 0.03 pulse-tick 
((57112953926593103094281339013663 . 35184372088832000000000)) nil 
41000]
[nil 24768 52135 937847 0.03 pulse-tick 
((57112954032995665628571964672543 . 35184372088832000000000)) nil 
679000]
[nil 24768 52139 121924 0.03 pulse-tick 
((11422590829005067355650957168339 . 7036874417766400000000)) nil 
746000]
Making completion list...
command-execute: Command attempted to use minibuffer while in minibuffer
Quit
Configured using:
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Load-path shadows:
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