[BUG] Fill-paragraph issue with hidden emphasis markers and composed characters [9.5 (9.5-b83ae59 @ /home/lucas/.emacs.d/.local/straight/build-28.0.50/org/)]

[BUG] Fill-paragraph issue with hidden emphasis markers and composed characters [9.5 (9.5-b83ae59 @ /home/lucas/.emacs.d/.local/straight/build-28.0.50/org/)]

[Lucas Viana Reis]

[-- Attachment #1: Type: text/plain, Size: 1952 bytes --]

Hello, I'm not sure if this is a general issue with fill-paragraph or with
the way org hides emphasis markers, but I'm facing this problem with bare
emacs + org:

Steps to reproduce:
1. Start emacs -Q (no configuration)
2. Set some variables:

(setq org-pretty-entities t
      org-hide-emphasis-markers t
      fill-column 80)


3. Create an empty org-mode buffer with the following text:

This is a /italic sentence for a buggy/ \alpha\beta\gamma\delta\nu\epsilon
paragraph in terms of filling, see, it's not filled yet and still the line above
ends early.


So far so good, and with the previous config the emphasis markers are now
hidden and the greek letters appear as unicode characters.

4. Hit M-q (either fill-paragraph or org-fill-paragraph, both have the same
issue)
The first line wrongly wraps after "buggy" and leave a big empty space
after that, as if the greek letters were not composed.

5. In the same buffer, compare the behaviour with this paragraph (very
similar, but note the ! character after "buggy"):

This is a /italic sentence for a buggy/ ! \alpha\beta\gamma\delta\nu\epsilon
paragraph in terms of filling, see, it's not filled yet and still the line above
ends early.


When I fill this slighly different paragraph with M-q, it wraps the text in
the right way and the first line is completely filled.

So the issue happens when a hidden emphasis marker is immediately followed
(maybe after a space) by a composed charater like \alpha. I am also facing
the same issue when the characters are composed by prettify-symbols-mode
instead of org-pretty-entities, and also with other types of hidden
emphasis markers. If org-hide-emphasis-markers is disabled then the issue
doesn't happen.

Thanks in advance!

Emacs  : GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
3.24.29, cairo version 1.17.4)
 of 2021-07-09
Package: Org mode version 9.5 (9.5-b83ae59 @
/home/lucas/.emacs.d/.local/straight/build-28.0.50/org/)

[-- Attachment #2: Type: text/html, Size: 8601 bytes --]