Dash-separated long list items rendered as sublist

[kdeldycke]

Here is a Markdown file with a list of very long items:

❯ cat ./dash-separated-link-list.md
- [Link 1](#link-1) - Description of line 1.
- [Link 2](#link-2) - A very long description for the second link in the list. That description is more than 80 characters wide.
- [This is a very long title, pointing to an awesome article on incredible stuff we're not used to see everyday](#link-3) - Line #3's description.
- [Link number three](#this-is-a-very-long-url-that-is-pointing-to-a-really-really-great-website) - Fourth description.

It cleanly renders into a list of 4 items:

❯ /System/Volumes/Data/usr/local/opt/cmark/bin/cmark ./dash-separated-link-list.md
<ul>
<li><a href="#link-1">Link 1</a> - Description of line 1.</li>
<li><a href="#link-2">Link 2</a> - A very long description for the second link in the list. That description is more than 80 characters wide.</li>
<li><a href="#link-3">This is a very long title, pointing to an awesome article on incredible stuff we're not used to see everyday</a> - Line #3's description.</li>
<li><a href="#this-is-a-very-long-url-that-is-pointing-to-a-really-really-great-website">Link number three</a> - Fourth description.</li>
</ul>

Now if I try to tidy up the original markdown into a 80-chars wide format, I get the following:

❯ /System/Volumes/Data/usr/local/opt/cmark/bin/cmark --to commonmark --width 80 ./dash-separated-link-list.md
  - [Link 1](#link-1) - Description of line 1.
  - [Link 2](#link-2) - A very long description for the second link in the list.
    That description is more than 80 characters wide.
  - [This is a very long title, pointing to an awesome article on incredible
    stuff we're not used to see everyday](#link-3) - Line \#3's description.
  - [Link number
    three](#this-is-a-very-long-url-that-is-pointing-to-a-really-really-great-website)
    - Fourth description.

Which renders into a list with an additional sub-list item:

❯ /System/Volumes/Data/usr/local/opt/cmark/bin/cmark --to commonmark --width 80 ./dash-separated-link-list.md | /System/Volumes/Data/usr/local/opt/cmark/bin/cmark
<ul>
<li><a href="#link-1">Link 1</a> - Description of line 1.</li>
<li><a href="#link-2">Link 2</a> - A very long description for the second link in the list.
That description is more than 80 characters wide.</li>
<li><a href="#link-3">This is a very long title, pointing to an awesome article on incredible
stuff we're not used to see everyday</a> - Line #3's description.</li>
<li><a href="#this-is-a-very-long-url-that-is-pointing-to-a-really-really-great-website">Link number
three</a>
<ul>
<li>Fourth description.</li>
</ul>
</li>
</ul>

This is due to an edge-case that is splitting an item content just before the dash located right after the link.

---

This bug has been reported first to the pandoc project at: jgm/pandoc#6497 . An interesting thing here is that the previous implementation was supporting this edge case while the new one based on cmark does not.

---

For reference, here the version of cmark I'm using, installed with brew on macOS Catalina:

❯ brew install cmark
(...)
==> Downloading https://homebrew.bintray.com/bottles/cmark-0.29.0_1.catalina.bottle.tar.gz
==> Downloading from https://akamai.bintray.com/3a/3af95418f96f4b0cec4bd76abaab312f3caf4cea591f38d3b725f15068d06491?__gda__=exp=1593691219~hmac=7f6c15036b995f36438e934f5bd44ec8
######################################################################## 100.0%
==> Pouring cmark-0.29.0_1.catalina.bottle.tar.gz
🍺  /usr/local/Cellar/cmark/0.29.0_1: 17 files, 724.9KB

❯ /System/Volumes/Data/usr/local/opt/cmark/bin/cmark --version
cmark 0.29.0 - CommonMark converter
(C) 2014-2016 John MacFarlane

---

This bug can also be reproduced with the cmark-gfm formulae provided by brew:

❯ /System/Volumes/Data/usr/local/opt/cmark-gfm/bin/cmark-gfm --version
cmark-gfm 0.29.0.gfm.0 - CommonMark with GitHub Flavored Markdown converter
(C) 2014-2016 John MacFarlane

❯ /System/Volumes/Data/usr/local/opt/cmark-gfm/bin/cmark-gfm --to commonmark --width 80 ./dash-separated-link-list.md | /System/Volumes/Data/usr/local/opt/cmark-gfm/bin/cmark-gfm
<ul>
<li><a href="#link-1">Link 1</a> - Description of line 1.</li>
<li><a href="#link-2">Link 2</a> - A very long description for the second link in the list.
That description is more than 80 characters wide.</li>
<li><a href="#link-3">This is a very long title, pointing to an awesome article on incredible
stuff we're not used to see everyday</a> - Line #3's description.</li>
<li><a href="#this-is-a-very-long-url-that-is-pointing-to-a-really-really-great-website">Link number
three</a>
<ul>
<li>Fourth description.</li>
</ul>
</li>
</ul>