fix emphasis closing by single _ (part of left-flanking run)

[RomanHotsiy]

Marked version:

0.5.1

Markdown flavor: CommonMark

Description

Fixes CommonMark: 456, 355, 451, 354, 356

Also, the concrete use case:

Some code: <code>*name*__b</code>. [link](/url/with_underscore)

Expectation

<p>Some code: <code><em>name</em>__b</code>. <a href="/url/with_underscore">link</a></p>

CommonMark playground link)

Result

<p>Some code: <code><em>name</em><em>_b</code>. [link](/url/with</em>underscore)</p>

Marked playground link)

Contributor

• Test(s) exist to ensure functionality and minimize regression (if no tests added, list tests covering this PR); or,
• no tests required for this PR.
• If submitting new feature, it has been documented in the appropriate places.

Committer

In most cases, this should be a different person than the contributor.

• Draft GitHub release notes have been updated.
• CI is green (no forced merge required).
• Merge PR

[styfle]

Hi @RomanGotsiy thanks for the PR!

It looks like the links to the demo have a slightly different input than what you put in this PR.

Some code: <code>*name*__b</code>. [link](/url/with_underscore)

Some code: <code>name__b</code>. [link](/url/with_underscore)

That being said, the fix the the link appears to work so I added a couple more reviewers.

[RomanHotsiy]

@styfle yes, updated the comment

[styfle]

Thanks Roman! 🎉

[RomanHotsiy]

Thanks for merging!
Do you have any ETA for a new release?

[styfle]

No not yet. We could probably do a patch release soon. Keep an eye out for a release PR...it will probably be from @UziTech

[kaelig]

This seems to have caused a regression.

Expected: https://spec.commonmark.org/dingus/?text=_foo_%2C%20_bar_
Actual: https://marked.js.org/demo/?text=_foo_%2C%20_bar_

Should I open an issue?

[styfle]

Yes please!

And if you could determine which CommonMark test this is violating that would be helpful 😃

This PR added many more passing CM spec tests so there must be one in there we were ignoring and now regressed.

[styfle]

@kaelig Looks like there is a ticket here: #1378