Formatting isn't applied if a line ends with exclamation mark, asterisk(s) and backslash

[roythedev]

Issue

• When ending a formatted text line with "!*\", "!**\" or "!***\" the wanted bold, italic or combination formatting isn't applied for backslash forced breaks.
• Escaping the exclamation mark doesn't help.
• Ending the line with two spaces instead of backslashes to add forced breaks works as expected.
• Issue is able to be replicated on https://spec.commonmark.org/dingus/

Test case (copy to the dingus)

***Failed to be bold and italic!***\
text

**Failed to be bold!**\
text

*Failed to be italic!*\
text

[jgm]

Simpler example:

*hi!*\!

becomes

<p>*hi!*!</p>

[jgm]

I do think this is a parser bug (also in cmark). The spec says:

A right-flanking delimiter run is a delimiter run that is (1) not preceded by Unicode whitespace, and either (2a) not preceded by a punctuation character, or (2b) preceded by a punctuation character and followed by Unicode whitespace or a punctuation character. For purposes of this definition, the beginning and the end of the line count as Unicode whitespace.

So the second * in this example should count as right-flanking, assuming that the \ is considered a punctuation character. (If we substitute another punctuation character, it works: e.g. *hi!*@.)

My guess is that \ is not being considered a punctuation character, and that is the underlying problem.

[jgm]

Clarification: cmark does not have this bug.