GFM remaining gaps

[ewjoachim]

Describe the feature you'd like to request

Working on https://github.com/ewjoachim/sphinx-github-changelog which now uses MyST, I'm looking at what GFM syntax elements are not supported by Myst yet, and I wanted to report them here so that someone, maybe, decides to add them. I'm not saying there is an obvious docutils node for each construct here, but I think it's useful to have an idea what the gaps are.

There's also a discussion worth having to see if some of the elements listed (the GitHub specific ones and especially the GitHub-repo) would be better implemented in a third party package to keep myst-parser independant from GitHub (apart that it is already bound by their syntax choices)

What I've found to be missing or different (in no specific order):

• Emoji shortcodes and GH-specific emojis (of course)

GitHub	Myst-Parser

• []() links: when GFM interprets them from a project file, / means relative to project root. Elsewhere (PR, comment, release), GFM interprets them normally, same as myst-parser

• In quoted code, it seems new lines are lost ?

GitHub	Myst-Parser
	(the lack of color is probably an issue from my side, I'm not 100% sure on this one)

• Footnotes crash myst-parser:

Here is a simple footnote[^1].

A footnote can also have multiple lines[^2].

[^1]: My reference.
[^2]: To add line breaks within a footnote, add 2 spaces to the end of a line.  
This is a second line.

GitHub	Myst-Parser
	Crash: changelog_text:71: ERROR: Unknown target name: "1". [docutils] changelog_text:73: ERROR: Unknown target name: "2". [docutils]

(Should this be reported as a bug ? Now that GitHub supports sub-issue, maybe we can make this a sub-issue)

• #336699 (hex color prefixed by # surrounded by backticks) appears as a specific color thingy in GFM
• @ewjoachim is a link to a GH profile page (@ewjoachim)
• https://github.com/executablebooks/MyST-Parser/labels/dependencies is replaced by a pill with the label name and color, linking to that URL ( dependencies Pull requests that update a dependency file ) (only works if the link points to the same repo as the current context of GFM
• #1135 (🚀 Release v5.1.0 #1135): links to issues/PRs/doscussions

---

Full markdown used in my tests

# Heading

*emphasis* / **strong** / ~~strikethrough~~ / <sub>sub</sub> / <ins>underlined</ins>
`#336699` / @ewjoachim / https://github.com/executablebooks/MyST-Parser/labels/dependencies / #1135

Emojis:
- 👍 (UTF-8)
- :thumbsup: (short code)
- :shipit: :octocat:  (GH specific) 

[Contribution guidelines for this project](/docs/index.rst)

1. List
2. Next item

- Unordered
- First

- [x] #1
- [ ] https://github.com/octo-org/octo-repo/issues/740
- [ ] Add delight to the experience when all tasks are complete :tada:


- sub 1
> [!NOTE]  
> Highlights information that users should take into account, even when skimming.

> [!TIP]
> Optional information to help a user be more successful.

> [!IMPORTANT]  
> Crucial information necessary for users to succeed.

> [!WARNING]  
> Critical content demanding immediate user attention due to potential risks.

> [!CAUTION]
> Negative potential consequences of an action.

| foo | bar |
| --- | --- |
| baz | bim |

> # Foo
> bar
> baz


```python
def x():
    pass
```

<details>
<summary>Details</summary>

Details

</details>

<!-- This content will not appear in the rendered Markdown -->

Let's rename \*our-new-project\* to \*our-old-project\*.

![Screenshot of a comment on a GitHub issue showing an image, added in the Markdown, of an Octocat smiling and raising a tentacle.](https://myoctocat.com/assets/images/base-octocat.svg)



Here is a simple footnote[^1].

A footnote can also have multiple lines[^2].

[^1]: My reference.
[^2]: To add line breaks within a footnote, add 2 spaces to the end of a line.  
This is a second line.

As rendered by GitHub

Heading

emphasis / strong / strikethrough / _sub / underlined
#336699 / @ewjoachim / dependencies Pull requests that update a dependency file / #1135

Emojis:

• 👍 (UTF-8)
• 👍 (short code)
• (GH specific)

Contribution guidelines for this project

1. List
2. Next item

• Unordered

• First

• Add initial parser code and tests #1

• https://github.com/octo-org/octo-repo/issues/740

• Add delight to the experience when all tasks are complete 🎉

• sub 1

[!NOTE]
Highlights information that users should take into account, even when skimming.

[!TIP]
Optional information to help a user be more successful.

[!IMPORTANT]
Crucial information necessary for users to succeed.

[!WARNING]
Critical content demanding immediate user attention due to potential risks.

[!CAUTION]
Negative potential consequences of an action.

foo	bar
baz	bim

Foo

bar
baz

def x():
    pass

Details

Details

Let's rename *our-new-project* to *our-old-project*.

Here is a simple footnote¹.

A footnote can also have multiple lines².

Describe the solution you'd like

• Closing the gap
• Someone to get inspired by this and make a 3rd party plugin that closes the gap
• Acknowledging in the doc that those constructs are not supported
• (Fixing the crash on footnoes)

Describe alternatives you've considered

(Not relevant ?)

Footnotes

1. My reference. ↩

2. To add line breaks within a footnote, add 2 spaces to the end of a line.
   This is a second line. ↩